I agree with OP that there should've been like... general consqeuences to killing/not killing but I like playing non-lethal regardless! Gives me the illusion of choice and may make me feel a little less of a monster for killing hundreds of people - I just knocked em out. With my 200k sniper shot. To their heads.
I was hoping there were consequences, I reloaded old saves to change the outcome a few times. Kind of a bummer it doesn't really make a difference.