1. More MIST. After the core release, by implementing "expanded armor absorbtion", you would allow players to obtain more and/or larger mist collectors on thier armor. Allowing more mist collectors would also allow players to collect mist faster, by gaining multiple points of mist every time they collect mist. An example (although crude due to lack of artistic entusiasm):

NOW-------------------------VS------------------------THEORY

Energy--------------------------------------------------Energy

00100---------------------------------------------------00100

( 99 )--------------------------------------------------( 149 )

----------------------------------------------------------( 119 )

----------------------------------------------------------( 99 )

After mist collection

NOW-------------------------VS------------------------THEORY

Energy--------------------------------------------------Energy
+1 mist-------------------------------------------------+3 mist
00100---------------------------------------------------00100

( 100 )--------------------------------------------------( 150 )

----------------------------------------------------------( 120 )

----------------------------------------------------------( 100 )

(This shows BOTH of the above listed ideas.)
In addition to that, if you are planning on giving players access to other planets/worlds after the core release, A Sprial Base of Operations could be created, which would allow players to store/withdraw Mist Energy(up to 1000) in a safe place so that it could be used for crafting high level gear. Alchemy Machines could be slightly tweaked to draw from stored Mist Energy PRIOR to using up Crystal Energy. This would also help emphasize the "FREE" of Spiral Knights.

2. Player Skills
Charge weapons are good and all, but what if you're group is about to wipe, you're the only surviving member with 3 pips in FSC, and you're surrounded by undead? Leviathan Blade isn't going to save you, even with a max CTR UV, so forget about it. But what if you had purchased (with CE) a skill that emits a burst of ear-shattering sound stunning all nearby opponents for 3-4 seconds? Now Levi Blade charge sounds like a plausable escape, due to its large knock-back AoE. This could be OP-stopped by allowing ONLY 1 personal skill per star level of combined gear (rounded down), to a max of 5(in case of updates adding higher star level gear).

3. Tank, ????, Dps?
I mean, this one's self explanitory. Where are the healers??? Heart drops are nice and all, but without decent health gains, your group is sure to fail in t3, so its hard to join a FSC group at a terminal and stay alive. This lack will only become more apparent in future updates, so I hope you guys REALLY consider this one soon. Heart drops make up for missing natural regeneration, but alone they aren't enough. Even with health items it can still fall short quite often, so either Natural Regen implemented, or provide players with the means of bringing healing gear for the group along with them.

4. Where my female avatars at?
Maybe a seperate version of armor sets designed just for Females? Everyone looks like guys, or run around looking like clones of each other, especially true for the Wolver set. Some players choose to keep the starting female avatar helm as a costume, which can sometimes look tacky on certain armor sets. Don't make it a nuisance for females to play this game. We need our women, for lots of different reasons :P.

For the most part, this was just a way for me to express my ideas on what I PERSONALLY think would help to improve the overall free-ness and enjoyability of SK. I hope you take it in to consideration and respond constructively to my ideas. Thanks for the great game guys, and keep up the good work.
(Edit: sorry for the chart, i got it fixed now.)