I think that this is not such a great idea. I like the idea of people being (more or less) locked into their handles. This way, their nick's carry a level of reputation and respect (or disrepute and disrespect, respectively). If you REALLY need to change your handle, create a new user.
Perhaps in the future, a system could be concocted that allows certain users to change their nick's, yet retain their rank and XP, in VERY special situations. My $.02.