Gamasutra has a great write-up of a Game Developers Conference Austin panel wherein Tracy Seamster of ZeniMax Online and Steve Danuser of 38 Studios talk massively multiplayer online game writing.
To me, MMO writing seems tough. There's just so much text to take into account like menu text, quest text and dialogue trees (to say nothing of scripting actual cinema scenes and race- or class-specific flavour text). Keeping the tone and pace of a game consistent across all of that and actually crafting a basis for a story or an instance sounds especially daunting. So no wonder both Seamster and Danuser had tons of examples of writing gone wrong in MMOs.
Here's a good bit:
Writers should "get over themselves", [Danuser]stated plainly. Instead of trying to saddle any single player with an epic destiny, the gameworld itself should provide a backdrop for collaborative heroism. Framing the narrative to promote teamwork, and creating narrative events that challenge the playerbase as a whole, allows for the epic tales writers crave.
Check it out, if you've got the time or possibly the aspiration to become an MMO writer.