Banned members getting a "I was an ass and now I'm banned" signature sound a bit harsh. And yes, I saw a member with that signature. No matter what that person did, he/she doesn't deserve to be name called. Would such a popular forum change into a forum for jerks? No, it shouldn't.
Maybe we can change that into "I broke the rule(s) and now I'm banned." You don't have to take my suggestion, but the banning signature should be changed.