IMHO the "move" link/tab on the user page is confusing and should be removed. I have already seen users trying to change their user name this way (I think this wrong way is intuitive for non-technically experienced users: Change a page title: move page. Change username: move userpage).
There is not really a use for moving a userpage; only when being renamed the user page has to be moved, and the bureaucrat has the option to let Special:Renameuser do that automatically. Note that this is only correct for normal userpages and _not_ for subpages in the User-Namespace.