To me, a big part of the appeal of Saints Row 2 is the whole "Just pick the character you like best and play that" aspect of it. Not just the visual customization, which is awesome, but the fact that you can choose from 6 different voices, that have full dialogue recorded for every cutscene and in-game bit of chatter, and even though the lines themselves are all more or less the same, the different voices all have clear personality differences in the way they deliver the lines.
More games should do stuff like that. Saints Row 2 is the only game I've played that really delivered on the "Play who you want!" idea. Well, so long as you want to play a sociopath.