Before I start, I do not post here often, so pardon my lack of forum ethics or traditions.
I apologize in advance if I should pretentious or uninformed.
And while I have not played regularly for quite a few months, I have purchased the dlc on my main account.

Background
From what I've noticed (and this is just what I have seen), this new dlc update has both drawn players back and cause others to feel alienated and leave.
The developers (OOO) have stated that a major motivator in creating paid dlc is to increase their presence on Steam. For those confused, this has to do with how many items show up when you search for Spiral Knights on Steam, as well as having the dlc show up on the news and new releases on Steam's front page.

The way the dlc is bought differs between Steam users and non-Steam users. Steam users will be redirected towards the Steam product page while non-Steam users are redirected to the Supply Depot (correct me if I am wrong). People that have bought the dlc can play the new expansion mission and enjoy the new items while people that haven't cannot be invited or even set foot in the expansion mission. However, the dlc may be gifted/traded through Steam trade (something that Spiral Knights highly supports), and OOO also have future plans for in-game gifting.

Proposal
My proposal hopes to provide an alternative to the paid expansion missions. I hope that the following proposal will convince OOO to try this alongside the regular paid expansion missions to see how well it is received and if it can truly replace said paid expansion missions.
My proposal is for OOO to release even more dlc! Before you mark me off as a troll or crazy, please continue reading. The paid dlc that my proposal focuses upon will not be about keeping expansion missions exclusive but rather aesthetic compliments and early access.

Problem
As previously mentioned, the problem in regards to the update is that people who have not bought the dlc or traded for it cannot access the expansion mission at all. While it may be silly to put off this as a problem simply because it is considered optional content, it is a very serious problem. People that have bought the dlc may think that the expansion mission was very well polished and may be more inclined to replay those levels rather than go into the clockworks. This is fine for now since there is only 1 expansion mission, but if OOO continues to release more and more dlc in the future, the community would be more segmented than ever before.

For example, there are 10,000 people in the game. 6,000 of them purchased the first dlc. and 5,000 people purchased the second dlc. 3,000 of those people also bought the first dlc. So right now, 2,000 people are restricted to the clockworks, 3,000 people feel more inclined to play the first dlc, 2,000 people feel more inclined to play the second dlc, and 3,000 people are free to move about both dlc. But then a third dlc is released, but some time has passed since then and 1,000 people have stopped play the game, and 4,000 new people started playing. 500 of those people had the first dlc, and 500 of those did not buy any. So there are now 6,000 people in the clockworks, 2,500 with only the first dlc, 2,000 with only the second dlc, and 3,000 people with both dlc. Now that there is a third dlc, 500 people with the first dlc buy the third dlc, 1,000 people with the second dlc buy the third dlc, 100 people with both get the third, and 1,000 non-dlc people buy the third. And so on and so forth. As you can tell from my example, the community will continually split up over the course of the lifetime of Spiral Knights. While one or even two or three dlc expansion missions can be fine, four or six of them will split the community up too much.
The assumptions that I have used:
-A fair amount of people have purchased the first dlc
-People will continue to purchase dlc
-Dlc will continue to come out every so often
-A fair population of people that have bought dlc will be less inclined to purchase two or three in a row
-People that skipped a dlc or few may be inclined to purchase the next newest one.
-A fairly large population of die hard free players will be less inclined to pay to play the dlc.
-People that purchase dlc are more inclined to play the dlc rather than venture into the clockworks.

Approach
Instead of paid dlc include exclusive expansion missions, dlc should be refocused to non-gameplay factors. In other words, the dlc should be changed into packages of accessories for both your knight and your guild. For characters, these packages could include auras, wings, and other accessories fitting a theme. For guilds, the dlc can be for decorating the guild hall, upgrading the guild hall, expanding the guild hall area, increasing the member count, and other guild rewards that will be mentioned later. Dlc themes can be in regards to holidays or the time of the year. Other options include reskinned items fitting the theme (with no additional functions), and havens rented out specifically for a guild for a set time period. Items can also have UVs separate from the 3 gameplay affecting UVs. Items bought from dlc can have a separate attribute that doesn't affect gameplay but is completely random for each purchase. For example, a reskinned pink leviathan can have UV Lots of Love Very High or UV Cuddles Med. This will create even more tiers of rarity and novelty that people have been asking for. Some other non-gameplay changing items can be also included. Although, as sugar-coating, people who buy the dlc will get access to the expansion missions a week earlier. So anyone who has bought a dlc within the past month can get into a upcoming dlc a week earlier than other people. Similar to how people who pay can get into a testing server. Some are detailed below.

Examples:
Valentine's Day dlc:
-Love Aura (2x) (One for gifting. Upon being gifted, it is bound.)
-Permanent Love Puppy Costume Helm (2x) (One for gifting. Upon being gifted, it is bound.)
-Special Interactive Comic
-Valentine's Day quest (Not expansion mission. Just simply requests like talk to a special npc. Or watch a cutscene. Or puzzle. And get a special artifact.)
-800 Prestige
-Pink Leviathan (reskinned. reward for quest.)
-Special Guild Hall accessory

Halloween dlc:
-Ghostly Aura
-Spooky Sound (mapped to an action button. Usable once every 10 mins. Only usable during Halloween special: time that punking is alive)
-Punking Puns Interactive Comic
-Halloween quest (Not expansion mission. Just simply requests like talk to a special npc. Or watch a cutscene. Or puzzle. And get a special artifact.)
-800 Prestige
-Spooky Acheron (reskinned with ghostly aura and different name. reward for finishing quest.)
-Special Guild Hall accessory

Winter dlc:
-Snow Aura
-Permanent Santy Hat
-Either reskinned Glacius or Triglav (random. reward for finishing quest.)
-Winterfest Interactive Comic
-Happy Holidays Message from OOO
-Winterfest quest (Not expansion mission. Just simply requests like talk to a special npc. Or watch a cutscene. Or puzzle. And get a special artifact.)
-Special Access to Party in a special locked Haven (reskinned) w/ the staff of OOO
-800 Prestige
-Jingle Sound (Mapped to action button. Usable every 10 mins. Limited usage within winterfest)
-Special Guild Hall accessory

Year of the Dragon dlc (if it was released alongside the ce special bonuses):
-Dragon Costume Helm
-Dragon Costume Armor
-Dragon Sword (reskinned leviathan. reward for finishing quest.)
-Dragon quest (Not expansion mission. Just simply requests like talk to a special npc. Or watch a cutscene. Or puzzle. And get a special artifact.)
-Interactive Comic
-800 Prestige
-Dragon roar sound (Mapped to action button. Usable every 10 mins. 250 times limited usage)
-Special Dragon Wings (separate from the ones given out for buying ce. Only difference is that slightly bigger and special name.)
-Special Guild Hall accessory

Regarding guild dlc is a bit different. Guild dlc should include decorative items for their guild hall, and other things that guilds have been asking for. Guild dlc should be able to be purchased with money as well as ce. However, the ce purchase would be significantly larger than the money equivalent. This will encourage the guild leader to purchase the dlc and be reimbursed by guild members in the form of ce. Decorative guild accessories could include chairs, paintings, lighting, banners, etc. Guilds should also be able to choose what they want their guild hall to look like. They can change it from a series of tilesets. Guids should also have levels. These levels will be increased by the amount of heat each member donates. When the heat gauge is maxed out, people will need to spend ce and crowns in order to level up the guild. Max level will be 99. Also, guilds creation should be increased from 500 ce to 1,000 ce AFTER the guild dlc update. But, as an added benefit of paying 1,000 ce, they will get a 33% discount for purchase of a guild dlc on steam or via supply depot. Guilds could also have minigames, all of these minigames will be available through regular pvp, but it will be something special for guilds to fight against themselves.

People may cry foul over how guild enhancements cost actual money or a very large amount of ce, but at least it does not include gameplay content. Although, an alternative would be to give them a 33% discount if they purchase the dlc within a week of it coming out, free guild achievements for every guild, and 2 free guild templates instead of giving them nothing.

Deluxe Guild dlc:
-10 random guild hall accessories
-Guild Hall Training Room Expansion
-10 guild hall templates
-Guild Expansion (increases the member limit by 100)
-World Announcement x1 (bound)
-Guild minigames (racing, tag, swings per second)
-Daily Guild Announcements
-Guild Bank (items fit into item slots, money can also be placed in)
-Guild Noticeboard
-Guild Statistics (stats on how many runs and such, when started tracking, when made, etc.)
-Guild Heat Amp 3 days x2
-Guild Summit Ticket (ticket for 1 representative from the guild to go to a private conference with OOO developers at a private Haven. Character to character. So things can be discusses as close to in person as possible.)

Premium Guild dlc:
-25 random guild hall accessories
-Guild Superbrawl (free for all)
-Guild Expansion x2 (increases the member limit by 100. not bound)
-Guild minigames (dodgeball, new racing templates, new tag templates, new swings per second templates, shootout, obstacle race, hide n seek)
-Guild Snipe Garden
-10 guild hall templates
-World Announcement x1 (bound)
-Disco Dance Floor Button
-Guild Exits (straight to bazaar, townsquare, haven east, arcade)
-Guild Bank Slot increase
-Guild Statistics Visual Enhancement (added visual effects for eye candy)
-5 hour Private Haven
-Guild Heat Amp 7 days x3
-Mass Messaging within guild
-Guild pvp taunts (for regular pvp when playing guild vs guild)
-Guild level up 2 (rare candy basically)
-Guild Summit Ticket (ticket for 1 representative from the guild to go to a private conference with OOO developers at a private Haven)

Results
As a result of issuing dlc that does NOT include any actual campaign/missions content or exclusive items, I think that people would not be so opposed to this. Especially after issuing the first dlc for paid purchase with a lot of the community upset, this would calm a lot of them down and possibly bring a lot of members back. I also don't think that people will be upset with the early access to expansion content due to a precedent (testing server). The special reskinned items and such have precedents in other games such as tf2 and even in spiral knights (scissor blade). The guild enhancements and such may also encourage users to buy more ce from OOO. The supply depot and featured auctions may also be used to sell the items from the dlc but without the UV rarities. While users may still complain by the amount of paid dlc, I don't think they will be able to complain about the game not having everything free to access if you are patient.

But I do use "I think" a lot so this is just my opinion and my suggestion. If you see a flaw in my logic and proposal, please inform me and we can discuss about what needs to be changed in order for this to work. Or if it won't work at all. Constructive criticism is greatly appreciated. Thanks in advance.