No one is saying that Itou is evil by default you idiot. Read back and be enlightened.
What everyone is saying that everything that he did after that was screwed up. He eventually became the way he was at the end BECAUSE of his actions and decisions. Sekai and all the other girls did have something to do with it, but they didnt force him to do anything. He CHOSE to do all of the stuff he did on his own. He is not an innocent child, he should have known better, but continued acting like a jerk.
And your argument about Sekai starting everything is pretty much shot full of holes. Read my and RZ's post to understand.
EDIT: And Mfauli, if you still plan to reply, please, please, try to refute the last criticism I gave in my previous post before saying anything else. Your whole argument is based on that, so if you cant refute it, anything you say will simply be pointless banter based on a fallacy.