My personal quote:
"If you cannot suprise the developer (yourself), then you will never suprise the player"
Emergent and procedural content is necessary for MMOs to continue. YOu can only do so many "pumpkin quests" regardless of the genre or theme of the game.
The key is to have solid, developed rules for missions\quests\content and have a systematic way to deploy that content for players to explore. No where in the rules of MMOs, RPGs, etc that ever fight need be winnable, rather that the payoff is acceptable to the player. So a well crafted Random Quest Generator, even in the event of an unwinnable scenario can still have a payoff for the player they can accept. Remember you can have adventures in which defeat is the outcome. (Case point Firefly fans, the whole story is driven by the fact they lost the war.)
Imagine an infinite dungeon that doubles it's difficulty every floor. There is a point that a player can not mathmatically continue (the point where the mobs would 1 shot you for instance) but the player is free to push as hard and as far as they want to go.
An arbitrary mechanism for mission\quest deployment is viable so long as there are controls (Mandatory Car References as needed):
Clutch: a mechanism in a quest in which the flow of events is disenaged and success\failure conditions cannot be effected. This is common in FPS where they put you in a room and you have to kill all the mobs before continuing.
Brake: A mechanism in the quest chain that allows the events to be suspended such that the player can do other things not impacting the quest(return to base for instance.)
Step Reset: A mechanism in which the quest line of conditions can be backed up (e.g. you accidentally destroyed a quest item in your inventory and you need another one)
Full Reset: A mechanism, depending on the nature of the quest to restart it (even if it is as simple as an abandon\re-get sequence)
Re-deploy: A mechanism to reset the position\staging of objects.
Triggers: Events that move along a story
Hitch: A mechanism that links two quests\missions together
Pay-it-forward: Always track the quest conditions to see if the player has already completed the quest (nothing worse then blowing up random named bad guy only to be told an hour later to go back and kill him. You did already!)
etc.... (I actually have a prototype Q-Engine that makes 3 passes to randomly generate quests. QE1 is the casting engine, Q2 is the linking engine, Q3 is the deployment engine).
Star Trek is about endless possibilities but at every turn they try to lock down the gameplay to conform to some IP that was never crafted for open ended, player driven game play. If you want Star Trek, go play Eve Online, seriously.
If you cannot suprise the developers, you won't suprise the players... it comes back around to more grinding then.