They all get repetitive, because every character is essentially just doing the same thing over and over, using different class mechanics.
The idea of making story a pillar of the game could feasibly be very interesting, particularly if different classes proceed in different ways.
The thing that I wonder is how interested hardcore mmo gamers will be in that story element, and in the cinematic presentation and voiceover. Because generally they don't even bother to read quest text, and I've known tons of people over the years that think quests in general are just a pain in the ass, and all they do is grind, pvp and raid.
I'm fairly hardcore myself, but I'm really looking forward to something in a game that goes beyond just killing the same things over and over for xp, loot or gear...