Does anyone use WordPress? In WordPress you can make a login name and also a "display name".
A Display name is what your name will be displayed as in the forums, like if you want the Login name to be different than the Display name.
What do you think?
Most people don't need it, and I personally see little reason for it...
Although I can see it being a more secure way of using a forum, I don't think many people will use it.
Why not just give users permissions to change their Username in the UserCP if they are looking for a way to change their name?
Well, some people don't need it anyway. But maybe in the future if this will be implemented, I suggest adding a feature in the ACP (to the Users Profile and Registration Settings) to enable to have a "Allow inputting a display name separate to the username (log-in).", for example.
Maybe some forum theme is integrated into WordPress blogs, or any other blog system which have registration enabled, and "the user's" display name is different than the log-in name so that feature might be useful sometimes in MyBB.