Honestly, I wouldn't pay a monthly fee for a KOTOR MMO.
But if I were too, this is what I think would be good.
have jedi and soilders as equals in combat. That said, you should have a very small amount of force points for force moves (this encompasses Jedi and Sith). Also, don't make Jedi as a starter class. if you want it, you should have to work for it. This'll help to turn the crapy players, who just want to go and kill everyone, away. I also think that there should be a limited number of classes.
Smuggler/trader (one in the same, you should be able to level up skills that would make you proficient in either one or both)
Scout/Scoundrel (one should be able to train skills to make him/her good in one or the other)
In each of these classes you should be able to level up skills.
Personally I would make the amount of force sensitive a random number of those who sign up (say 10%). I know alot of you will disagree with me about this last part, but these are my opinions nothing more.