Number One: Team Size is TOO SMALL.
MMOs have been around for a while now, and entire Guilds are switching from games like WoW, LotRO, CoH etc. to play SWTOR.
That means a lot of folks are hoping to play together at the same time.
Here's the math:
Our CoH guild alone has ported over 33 players - that's 33 paying accounts, if the Sales Department is listening - with 14 of those players being couples, generally with at least 8 Guild members at a time being online and our typical team size is 6 to 8 people, which means split teams, which means not playing together, which is not why we form a Guildd or, indeed, subscribe.
Team sizes need to go to AT LEAST six, optimally eight (8).
Number Two: All-or-nothing battles.
A team of four fights a Boss. One teammate dies. If the Boss isn't already below 25%, you can pretty much assume a 50/50 chance of a Team Wipe, because - incredibly - there is not in-battle resurrect. Well, also because the "cooldown" mechanic on heals is an ill-advised WoW carryover, but it would be tolerable if teammates could be revivied in combat.
Number Three: Successful Play Requires Perfect Builds.
Some will dismiss this as "bring the right build and stims and team and play better", let me say that is not the solution; it is the problem. A "perfectly structured solution" to a problem is a poor game design. When a movie monster can only be defeated one way, that's fine, but i am not paaying to watch a pre-plotted movie; I am paying to play a game with - hopefully - multiple paths to a given outcome.
I can apreciate that this is an illusion in the storryline - multiple choices may enliven the play, but do not alter the ultimate outcome - but in a battle, it's weak design.
If the only way I can win is the GMs way, why bother to play? I may as well just watch a movie.
Rant over.
But the team sizes need to be increased AT LEAST to six (6).