I seriously wonder what people have against a timeless, stylized look. It's one of the reasons that WoW still looks great today in spite of its very low polygon count.
Stylized art styles add characterization and personality to the game over a more "realistic" approach, while keeping the game a healthy distance away from the Uncanny Valley. It also ages VERY well, because the art is more about the style than it is about the polygon count; as the polygon count drifts away from the "current" technological peak of each successive year, the style never changes. ESO, on the other hand, I can almost guarantee that it is going to look pretty bad in a couple of years from now.
Ugly is purely subjective, so I'll give you that.
Non-mature, however... I for one think it is very mature to give your game a "face" that ages well. Good business move!
I, personally, enjoy the stylized look better than the "realistic" look. Because it's just "realistic". It's never real enough. If it ever gets to that point, then it will be either really weird or really cool...
(And I like the jokes, etc., in Wildstar and games like that. It's not "immature", it just has a sense of humor. )
A friend of mine once pointed out that going more realistic with graphics might not be a good idea.
The more realistic it looks, the more realistic we expect the game (and the Characters) to behave. The more options we expect to have.
We will be more critic of "missing" questoptions/RP potential, game limits (like the piranja wall at sea) and misplaced characters (like a questgiver we killed in story still being where we first met him) in a game like ESO then we would be in Wildstar.
Also for me it feels as if ESO is a bit shy about being a MMO. It is very well developed for it's 3rd month of being live.
But stuff like not tracking groupwide mana/stamina by default seems odd. It's not that they could not do it. It is like they don't want to do it (because that goes into MMO powergaming territory).
Personally I prefer fully voiced dialogs with some moral decisions. It was one of the reasons I played SWTOR that long and even invested som money into Unlocks.