My ideas for KOTOR III:
1) Character appearance selection should be similar to the one in NWN. This way you could choose your characters face, hair stile and hair color separately which should alow for more diversity.
2) Different robes, and by this I don't mean one robe type with 3 or 4 different color schemes. Also, make Dark Jedi robes look different from Jedi ones. Make them unique and not just black colored Jedi robes.
3) The ability to choose your own race. It would be great if you could make your character a Twi'lek, Enchani or some other humanoid or human-like race.
4) Better masks (the only good looking mask I've seen so far is the one worn by Darth Nihilus)