I, myself, am surprised at the graphics of ESO when I was playing in beta. It is much better than I expected.
You must keep in mind the fact that the game must run smooth for as many people as possible, so therefore, they got to reduce the graphics slightly.
I do not think you should worry about the next singleplayer TES. I am sure it will be good and is coming along just nicely.
Gotta keep in mind that the company that makes ESO is not the same that makes the singleplayer games.
As for the quality of ESO... I guess I will take a personal look this weekend.
Thank you kindly.
I am looking forward to it myself and I have the same views as the ones you listed. Immersion, exploration and playing with friends.