Fr33styler: I really love the idea of mission story based where 2 teams tries to complete theirs first, but i'm not sure how hard it would be since it needs some randomizations and yet a solid idea of what you're gonna do
Yunipuma: This will be shit. Because it is already exists - so called "flashpoints" in MMO Star Wars The Old Republic. Nobody waits for new player to see cutscenes & understand what to do, everyone just run ahead. Team work is some unknown shit. Ragequits. Etc, etc.
That sucks, but I think you will always have similar issues regardless of how multiplayer is implemented. (I don't know of any MP game where nobody rage quits and nobody is impatient with new players. Would it help to have leveled match making (this would rely on nobody having secondary/smurf accounts, and there being a large active player base)? How about penalizing leaving an ongoing match in some way (not sure I'm a big fan of this idea)? If you made the cut scenes short, you could maybe make them unskippable (again, not a big fan of this idea either).