Here is my suggestion on how to fix the biggest core issues with ESO.
The first step is to stop damage scaling with resources. This is one of the core problem with the current game. Making skills scale with level, spell damage, and weapon damage would not only make the game far easier to balance but would instantly fix a huge amount of the problems with builds. This would allow people to simply use resources as resources and not worry about stacking a certain one for increased damage. This would allow for people to easily mix weapon, guild, magic, and class skills without feeling like they are going to lose out on damage. It would also allow for much broader gearing and we would see the use of different armor types and weapons immediately.
The second step is to stop having all of the class skills in game work off of Magicka. The most simple fix would be to make the skills that work off of weapon crit just use Stamina and Weapon Damage. With Stamina just being a resource (step one) it would easily allow for more creative builds that utilize Stamina and Magicka. As an example a Nightblade that relies on the "melee" class skills they could easily put these together with weapon skills and make a cohesive build. In the current setup you would have to load up on Magicka, Spell Damage, and Weapon Crit to increase the class "melee" attacks while having to load up on Stamina, Weapon Damage, and Weapon Crit for any weapon attacks. Hybrid builds would truly be able to shine because you could easily use both Magicka and Stamina based abilities without having to worry your resource pool is hindering your damage output.
The third step is to remove sneak, block, dodge and sprint from Stamina and create a third resource. For the sake of this discussion we will call it Endurance. Have different armor or weapons reduce the Endurance costs. Some examples are Medium could reduce the Endurance cost of sneak. Heavy could reduce the endurance cost of Block. Light could reduce the endurance cost of dodge roll. One hand and shield could reduce the endurance cost of block. In the current setup a dedicated Magicka build can actually use 100% of their stamina pool for defense, sprinting, and sneaking and never have to worry about running out of a resource to do damage or heal with. This is just one more thing that is pushing people towards Magicka builds, light armor, and staves.
These three changes could fix a huge amount of the issues the game currently has. I could go on to smaller more detailed points but I think these three changes could start to move ESO in the right direction. I think this game has the potential to be one of the best MMOs in history.