"MUST NOT DO
1) No automation of group formation with random players, especially random players from other servers. You only want to automate the "desire" to run a dungeon, not the party formation itself."
To add to this, one of the things that killed wow (for me), was teleporting to the instances via dungeon finder.
Running from one continent to the other, pvping along the way was so nostalgic and fun. Raid groups warring with one another on the way to the raid entrance, I miss those BWL nights. I would hate to see this taken away. Kinda like flying mounts, they are fun, and let you get to places you normally couldn't, but it takes away world pvp, a major part of any mmorpg.