I've played a great deal of T3 Lockdown, not the best by a long shot but definitely one of 'those people' that people come on the forums and gripe about when they say Lockdown is imbalanced. Lockdown is fun, but it could be better! And without my dev effort! :D. So here's my laundry wishlist.

1) Join as group. You would put together a Lockdown party and away you go. This would be different from the Guild v Guild option in that you'd still be split normally across the two teams, this would just provide an easy means for people who like to play Lockdown to play together. Right now it's either pure pug (and usually there's more than 1 lockdown game going in T3) or guild vs. guild. You would also be able to join your friends if you got an invite from them, provided you were willing to wait until their current game was done.

2) The loadout system confuses the hell out of people. Lots of people think they're queuing for T2, but they have a T3 loadout so they get hammered in T3 and wonder wtf happened. Or they think they're queuing for T2, but they have a 4-star helmet or something and get thrown in T3 even though the rest of their gear is T2. Or they lament their gear is locked even though you can set up all the loadouts you want ahead of time and switch between them inside of Lockdown at will (so long as you're in the locker room)

2a) There should be some kind of tutorial that explains how to use loadouts and what they're for. It could be like the advanced training hall where people can practice with their roles as well.
2b) It needs to be very, very obvious what tier of Lockdown people are queuing for, and an option to go to said tutorial if they're confused.'
2c) In relation to 2b, if people are queuing for a higher tier of lockdown than the lowest non-trinket item they have equipped, a confirmation dialog box should pop up, saying something like "You are queuing for Tier 3 lockdown, but your armor, helmet, weapon 2, weapon 3, and weapon 4 are rated at Tier 2. Are you sure you want to queue?"

3) More maps, more varied gameplay. You could have a map that has the 5 energy turrets on it you can activate to defend your nodes, you could have a King of the Hill-style map that only has 1 node, you could have nodes + CTF (like Eye of the Storm in WoW), etc.

4) More stuff to spend Kromgo Coins on. Mod Calibrators aren't as good of money as they used to be, and we should be able to buy consumable pvp stuff anyway. Consumables should be cheap to encourage people to use them. Some suggestions:

2 Coins - 5% buff to health/speed/damage (pick one), next match only
5 Coins - Energy rez at half cost (single use)
5 Coins - Cap nodes twice as fast, next match only.
10 Coins - Throwables / pills. They'd appear in your pickup bar whenever you join a lockdown match until you use or drop them. You could drop them if you like and your teammates could pick them up. Unused items would be stored between games.
10 Coins - +3 / +8 / +18 vitapod (T1/T2/T3), next match only
10 Coins - Energy rez at no cost (single use)
10 Coins - Applies a max UV of your choice to an item of your choice, next match only.

5) The matchmaking system should, when enough people are playing, attempt to group people by their gear. This doesn't need to be anything complicated, it could just add up the star rating of all equipped gear, add 1-5 points for each UV (low being 1, max being 5), and then just group people in order. While there's often barely enough people playing to keep 1 T3 game going, on weekends and primetime this may cut down on the noob stomping just a bit.

6) Accessories. I'd suggest 1 pvp-specific accessory of each type (Maybe call it Deadly or something), with a cost corresponding to its general rarity. Wolver tails and wings could be 1000 coins, maid headbands could be 50 coins.