1. No Jedi would ever consider genocide to be a justifiable solution.
2. He was forced to live three hundred years, and the only reason he wasn't even more insane from the Emperor's torture was because of Meetra.
I enjoyed playing the original KotOR just as much as the next guy, but Revan was a medium sized fish in a very small pond in KotOR one and two. As soon as he encountered the even bigger fish in the Empire, he got spanked. Hard.
Like Qui-Gon said, "there's always a bigger fish", and it isn't Revan.
Revan's only attraction is how 'uber' he was meant to be, but when you clean off all the layers of praise and actually look at his canonical feats and prowess, he's nothing more than a puppet to many people.
He is a poorly written gary-stu that is heavily over-exaggerated.
Meetra did all the real work anyway.