An opinion you're probably all alone with?

[Vinyadan]

Heck, by mid-game (about level 12) in Morrowind I can reliably kill at least two ogrims with a single mana point.

Assuming you mean magicka point, I am confused about how this is possible, given that Ogrim have at least 170 hp and spell cost doesn't decrease with better attributes or skill. Did you mean spell, or bar?

As for fatigue, in Daggerfall it only regenerated while resting. Personally, I think that such a system would make sense if it were tied to other survival elements like food and water, with a rework of weight, encumbrance, and maybe spoiled food mechanics.