Eso combat is amazing for a bit, but at a certain point any class you play is going to feel boring and repetitive if higher numbers is all you are pushing for....
even more so i think with the new class coming out because all of its abilities look the same pretty much visually and there is a system that rewards you for using those "non diverse" class skills...
so say that i wanted to play a class that had unique skills like the arcanist but wanted to focus on a different visual look or damage style; how would i do that?
Spell crafting
this could be a great way to add variety to a classes look and a number of new "morphs" to its skills
ex. Arcanist could use their rune style magic but with different visual effects to match with fire, healing, magic, etc through a system that lets them learn how to modify their base class spells...
Doing something like this would add so much more depth to each classes' combat and as a result would create less demand for classes in the future.. Some people are still going to want a bard style class though...
So at the end of the day a class has its specialties but two three or even four people at end game playing the same class can have completely different looks..

This should be a base game feature as the way i would do it is that you learn new class spell morphs from studying non class skill lines...
you would still be locked out of some options as some skill lines like psijic are dlc but at the end of the day everyone has more depth to their playstyle..

for more info on how i would impliment spell crafting visit this post and feel free to comment on either post
https://forums.elderscrollsonline.com/en/discussion/622494/edited-repost-of-my-abitity-merging-idea#latest