Display name =/= ID.
Display name is what shows when you chat with your friends. ID is what you log in. ID stays the same. Display name or screen name or nickname should be possible to change whenever you feel like it. MSN does it, Skype does, ICQ does it, everything I've used until now does it. Even the old yahoo did it. And now I have to show either my full name or my ID to my contacts without the right to change the DISPLAY name? That's stupid. And it's a hole. Big one.