the classless system where you can be anything you want as long as you are willing to take the time.
the same lvling system where you gain skill by using those skills andand after so many skill ups you can lvl up and chose the attruibetes.
make it some servers NO PVP and some semi pvp (no free for all pvp no full loot corpse etc etc)
1 man 2 man 6 man 24 man (raiding) capable
HUGE open world playablilty
anyone that thinks tes would be a bad mmo is crazy elder scrolls would make the best game if made right and i doubt they would do it badly. for the most part the players are fine if they arent then /ignore forever and be done with it.
in the last 6 mmo's i played i would comment on an morrow wind type mmo same style same system same tye of world everyone that responded in open chat (lots of people) were like oh my god that would be the best