your account name is not the same as your display name, which you can customize on a per-server basis. Also, signups are done via email. And your "username" is not unique by design, it gives you a numeric identity alongside it (much like how Blizzard's battle tags work).
I wish you could also change your profile picture per-server. I'd like to be able to use the same account for work and play, and this is my only blocker.
