They have inappropriate words in them. Do you not care if children see this?
~ @Toostenheimer
I do not. It's a game. Are you telling me that children will think about a Minecraft username so much that it will affect their life? If you are playing this game, I am expecting you have heard or seen a bad word. Honestly, it's the parents' fault if their child sees a bad word.
Actually, Onis said that if you change your name, your rank, meebles, and all other data will be lost and any player can recover it.