I think that's doing the game a disservice. In a universe defined by simplistic, binary morality, KotOR 2 was the first a Star Wars product which acknowledged that - in the end - EVERYTHING about the setting amounted to blue lightsabers clashing against red lightsabers. It saw right through the inherent absurdity of the material and offered a concept that (as far as I know) no other franchise writer would explore again: that perhaps the Star Wars galaxy would be better off without the Force, whether light or dark. If the entire canon is just hundreds if not thousands of years of technicolor space wizards tearing each other apart, with no real progress happening, then what does this say about the Force? What is the point of it all?
Ah, right.
KotOR 2 took a popular video game series in a huge media franchise and found the stones to say out loud "hey, here is why it sucks". However, more than anything else, it also showed that the setting had potential to grow beyond its constraints - it offered a glimpse into what a mainstream Star Wars story could be if it wasn't afraid to ask questions instead of regurgitating the same old lanes of "Self-Insert OC Jedi #13 fights Wish-Fulfillment OC Sith #32".
Sure, some people would say that it's not exactly groundbreaking and that Avellone simply rehashed his staples (Ravel -> Kreia etc). Still, to me, it's quite an extraordinary effort when you consider that the game managed to successfully elevate stuff that George Lucas thought up on the spot in a phone call.
EDIT: I read the post below. I was talking out of my ass - KotOR 2 wasn't the first. I stand corrected.