If you don’t think your PSN username or Xbox gamertag are very appropriate to be used as the name of your Destiny guardian, you may be out of luck, as Bungie just mentioned in the Q&A of the latest Weekly Update that renaming your character will not be possible unless you change your nickname on your console of choice.
You are your character in Destiny. In your case, your Guardian will be named F12. If you want your name to be more colorful or personal (i.e. NinjaSniper420, Titan Nick, Robert Paulson) you need to change your identity at the source. Our hope is that you have an identity in the game that’s meaningful to you, and that new friends can track you from your favorite Destiny forum to a rendezvous in orbit over your favorite destination.
While I’m not sure how large the roleplay community will be in Destiny (but as a veteran MMO player and roleplayer I’ve seen RP communities flourish literally anywhere), I can’t see them being too happy about this.
While I understand that Bungie wants to make it easy to find one’s friends in game whatever character they may be playing, it’s kind of inconvenient to be bound to an username when we’re playing a character that may have nothing to do with him or her.