First off I'll say that I've been playing ESO for a while and quite frankly I don't understand the negativity. I've played alone a lot, I've played with friends and I've already got plenty of hours in the game. Obviously there are areas where it is lacking, such as the loot/item system where we as TES players are used to picking up whatever we want whereas is ESO most of the prettiest stuff we find in the game cannot be picked up. Which does svck somewhat but it 's a typical MMO feature.
However, I find the magic in ESO to be far more satisfying than the single-player games. The ability to mix abilities using magicka, stamina and magical items like staffs makes me feel so much more like a proper 'Mage' than the one-spell system of Morrowind/Oblivion and the two-spell system for Skyrim. Being able to change between spells without menus and having spells that work well with each other, for example a spell that knocks down an enemy while you drain their health with a staff, followed by an AoE spell to deal with more enemies. I also especially like that staffs of specific disciplines have their own skills and unlockable abilities. Basically, I find the range of spells and the ability to use multiple at once a great improvement. I feel like something similar and more attuned to single-player games would be a major benefit to the franchise. And spellmaking wouldn't hurt, either.