Some other MMOs have dabbled with player-generated content, to various degrees of success. Coty of Heroes had a pretty amazing system for this. There were a lot of farming quests generated with it, sadly, but some awesome narrative focussed quests too. Sadly that game is no more. I believe Star Trek Online has something similar. It's a great way to extemd an MMOs conyent for people like myself who play for story, but it needs commitment from the devs to make it work.