It would be funny if the game creates random players AND random characters for those players. For example, a player might work 9 to 5, have 3 kids, a wife, a cat, and only play on weekends. Every so often, the cat runs across his keyboard, causing whatever character he is 'playing' to mess up really bad. I would give the players randomly generated personalities. You can meet a kid who never typed a complete word in his life. There is woman who constantly complains about her lazy husband and sucks at playing but has every perk unlocked because the MMO is her life. One guy tells everyone what to do, then gets angry when someone disobeys, but is almost always right and has awesome characters.
The real game could be about managing fake players. Make a guild. Recruit decent players with decent characters who can actually play when you do. Deal with their personal problems and scheduling issues. You would spend as much time monitoring the fake chat as doing normal game stuff.
A game about the game. There's probably a movie in this idea, too.