K i'm not sure if anyone would agree with me on the point i'm going to make.. see the fact is that when people talk about a "persistent" world, which is ultimately static - they're talking about a very wide view, i.e. the one that GMs and the creators of the game have..
In reality an MMO world is just as progressive from an individual player's view as any linear single player game. Once i've finished slaughtering koltar in the barrens, and stolen their measily scrap of flag from the leader's body - i go back to the cross roads and hurrah! everyone's happy

then i move on from the chat infested "barrens" to the next area - confident that i completed a quest, and made an impact like in any other game, during my progression through it. The fact is that it doesn't matter how many people then complete that quest after i do.. their overall experience is separate from mine.
This also extends from solo to group and raid content.. the feeling of huge yet static world is dispelled by the fact that you're only ever experiencing it with a limited number of people, from a limited perspective. Yes, Orgrimmar is filled with players who have raided every dungeon in the game (probably), but the experience for an individual player and his equally equipped guild mates is still one which is progressing through a fairly narrow and linear storyline.
Just a thought.
On another note, so long as a cut scene is well done, i really don't mind them being there.. especially in games which have a more "removed" player perspective anyway - like in strategy games for instance...