Letdown of the Decade
Simply put, they tried to push the envelope too far. They tried to let you be literally ANYTHING you wanted to be. And the real problem is that everyone came in this wanting to be only a few things.
Jedi
Sith
Stormtrooper
Pilot
Smuggler
Bounty Hunter
Commander
Wookie
Ewok
Some of those things you could do. Others you had to dedicate your whole life in order to do them. And still others weren't even on the menu. Pilot was the really big one, and you couldn't even do this until the expansion pack which took wayyyy too long to come out. The combat system was broken from the ground up, and the building system while really interesting and innovative, never really came together the way one would hope.
The result was a very sad game that had SOOOO much potential. Hopefully the game development heroes who made KOTR will make a better one this time around.