That got your attention. So why would I make such a bold and daring comment? Simple: Dungeons, group content, "Raids" and more (note the quotes around Raids). These types of activities require you to in some form have some who is wearing heavy armour to take the argo, some one with the staff to heal and finally who ever for dps. Lots of MMO's don't have this trinity aspect - but it is known that if you plan to be a mage - you have to play your role in dungeons, you cannot be some heavy armour - duel sword wielding fireball thrower. people expect you to stand back, either heal or cast your spells from a distance.
Even in games like GW2,. where there is no trinity, a lot of the times when I play my caster class, I am expected to stay at the back and support the team - regardless of my ability to go in, lay down some what ever and get out alive. People don't like that. People don't like change in group based content. they want to be healed, they want the tanks, they want the dps people.
No in the open world, sure you can be your heavy armour wearing mage who wields axes and goes crazy, but if you like group content you'll be asked to switch and after enough times of switching up your gear youll just start playing that role out side of dungeons - which ruins the elder scrolls way of doing what ever you want how ever you want.
I haven't done group content in beta, so maybe I am completely wrong - please state that if so, but I get a feeling I am not.