I think the concept of MMO and RPG mix like oil and water... you can toss em together all you want, stir them up, but they still won't work.
Your 'role' in the typical MMORPG is demolished by the fact that everybody else is playing an equally important 'role'. Make an RPG with one to ten people together and sure, you have some memorable characters who can make a difference in the world... but massivly multiplayer games make you a faceless hero in a world overwraught with mindless, eternal peril which you can never fully overcome.
While you are still technically playing a role, it's not one very suitable for an epic adventure. You can't all be built into the central storyline. You can't all be heros. NPCs treat everybody equally. Personality has no development, only skills.
So my point is stop wanting to make the ultimate MMORPG, make another kind of MMO, one more focused on gameplay and interaction. I suggested something like this
here if you care to see some ideas.
Just my opinion. I do enjoy MMORPGs, although I think enough is enough. Move on, and think of more suitable genres to go with MMOs.
As ever,
**Cosmic**