Everyone has wish to change his username, but I think Admins change only the usernames of staff members.
partly right. Admins change the name of staff members only when it's hard to remember, since it's preferred that a staff member can be easily referred to, and talked about. Like say if this dj guy become a mod, his name can be quite a confusion, so we might give him a username change. However we can't do that to every single players out there, and there are no need to do that also.
abusive and inappropriate names will also be changed as well.