The clone wars is in the future with respects to this game, period droids tend to be clunky and slow, imagine playing as C3-P0, slow and annoying. Greivous could use lightsabers but not Force powers, droids do not connect to the force, and a Jedi or Sith without the force is not much fun.
I agree more races would be fun, and I love the idea of Imperials be swarmed by hundreds of trooper "Yoda's". Out of interest what is Yoda's race called, please someone tell me?
I realize Droids don't have force powers, and therefore can't be Jedi or Sith. But you could still play a Droid with lightsabers, which I agree would be pretty stupid, but it can still be done. C3PO is a protocol Droid, so I wouldn't expect much agility from him, but I see no reason why Droids of this era must be slow and clunky. Look at the HK assassin droids, they seem to be able to perform at levels similar too Imperial Agents and Troopers, so why couldn't droids be a playable race for non-force wielding classes?
Science doesn't advance much in the Star Wars universe, the era our game takes place in is pretty much just as advanced as the era the movies take place in. I believe they have a sci-fi name for this type of society, one where its so advanced that the evolution of technology comes to a near halt, but whatever it is slips my minds.
Yoda's race has no name, on the wookiepedia there simply called "Yoda's Species". Perhaps casual gamers would think its cool to have a bunch of Wookie smugglers and cute Ewok Jedi or Yoda troopers. However it would feel lore-breaking and remove from the realistic Star Wars atmosphere of the game, and the mystery behind the species, in my opinion. It would be better to add more common and mainstream races such as Rodians and Togruta.