ESO is the first Elder Scrolls game to use so-called "Ultimates". But where did this concept come from?
Health, Stamina, and Magicka are series staples for resources. Spells, Lesser Powers, and Greater Powers are series staples for abilities.
"Ultimate", whether referring to the resource or ability type, is a lore-breaking loaner word borrowed from other genres. It doesn't fit the fantasy theme of Elder Scrolls games. ULTIMATE! I can't help but picture some cheesy Street Fighter scene.
A simple lore-friendly fix would be to replace the term Ultimate with Power. You gain Power from combat and use it to unleash Power abilities. That would have been consistent with Elder Scrolls lore and the fantasy genre, and there's no earthly explanation for why this wasn't done from the earliest stages of game development.
There is another lore-friendly alternative worth considering: Dawnbreaker is an Artifact, providing a nice template for another possible system that could've been used. You could gain Favor from combat and use it to summon powerful Artifacts. That would also be consistent with Elder Scrolls lore and the fantasy genre. If such a system had been implemented from the beginning, we could all be accustomed to playing with a familiar collection of Daedric and Aedric Artifacts instead of cringe-inducing fighter-game "Ultimates".
This isn't comprehensive, but some examples to show how this could work with existing artifacts from the lore (and new ones could be created, too, to fill gaps where there is no obvious choice):
WORLD SKILLS
Mage's Guild: Staff of Magnus
Fighter's Guild: Dawnbreaker
Vampire: Mace of Molag Bal
Werewolf: Ring of Hircine
CLASS SKILLS
Aedric Spear: Chrysamere
Restoring Light: Lord's Mail
Dark Magic: Black Book
Summoning: Spear of Bitter Mercy, or Sanguine Rose
Shadow: Ebony Mail
Assassination: Mehrunes' Razor
Siphoning: Umbra
Ardent Flame: Goldbrand
WEAPONS SKILLS
Two-hander: Volendrung
Bow: Auriel's Bow
One-hand and Shield: Spellbreaker
So given the lore-friendly alternatives, Powers or Artifacts, why do you think ZOS decided to borrow the lore-breaking idea of "Ultimates" from fighting genre games?