General impersonation of others is flawed. As much as it would help the more "evil" players, it would also open the game up to easy ooc grieving. Anyone could then simply impersonate anyone they wanted. Say I wanted to play impersonate the Karyuu. I highly doubt she'd appreiate someone else runnig around under her name, cuasing all sorts of problems. Sure the older people might figure it out that it really wasn't her, but what about all the others that don't know. They think it really was her, and thus she'd be spending all of her in game time clearing up stuff and regaining trust to everyone every time she was online. A game is supposed to be fun, not a chore. The minute you deprive others of that fun, you are a griefer, which is a bad thing to be.
So with your impersonate idea, not other players, but perhaps it could allow for you to pick a random name or something that another player isn't already named. But even with that, people could simply put you on thier buddy list and when you change your name, it changes on the buddy list, so they would still know. But then again, the buddy list is ooc, so that the player would know, but the character would not. Asumming we are all the best at being able to diferenciate between the character and player (

), this wouldn't be a problem.