I think the key is the avatar. If people change their name, they need to keep their avatar, or else it's a dead-end.
I'm already so confused by all the username changes, but this is a feature requested for SOOOO long by many people, I do support it because I think it's a benefit. I read somewhere statistically that like 70% of deactivated accounts are because people wanted a different username.
I have been Mirz since 1998 on the internet. No sense in changing it now.