One newer feature MC has that I will say I think has been abused, to an extent, is changing usernames.
Way back when, the only way you could change your username was to either put in a request to Phil and see if he would granted it, or abandon your current account and register a new one with a different username (and hope it doesn't get deleted for being a sock puppet account).
Either way, it was incredibly difficult to change usernames, because Phil wanted to avoid confusion among the community, since we all get used to each other's usernames . . . but once he implemented the ability to change our usernames (albeit, with a limit of three times), and people began changing their usernames right and left (and some already doing so more than once), that very confusion began happening.