Actually, most sites I'm on won't let you change your username willy-nilly. They require a very good reason. I'm surprised that the admins here will do it on a whim. Running a site is a pain in the butt, and doing optional tasks like name changes are simply one of those things that many will not accomodate. Or is there a way to change our own names? If so, I can't find it. Sigs and avatars, on the other hand, are something we can all change ourselves, so its no burden on admin.