Sure, it could be done, but how many MMORPG games have you seen out there that allow you to change your name during the game? I personally can't think of one and why is that? Because it's a bad idea. Even if you change all names in the log files and in the database you still have the memories of players and GMs who suddenly won't be able to find a certain character/account any more because it's name has changed. To prevent that we would need to keep an extra list to record all the names a certain player has had. And what if player A chooses a different name and player B picks player's A previous name -> identity theft.
To sum up: allowing players to change names of characters/accounts is a terrible idea.