And Morrowind is the worst implementation of Fatigue in the entire series.
How so? In Morrowind fatigue actually had NOTICEABLE effects. Was fatigue a wasted status bar in Morrowind? Mostly. They should have done it better and had it mean more. But in Oblivion, I never once paid attention to fatigue. It never effected me in a way that I noticed and cared about. If anything I'd say Morrowind had second worst implementation, though I don't have nearly as much play experience in Daggerfall and Arena. At least in Morrowind being tired effected you outside of mathematics (spell chance, jump height/distance, etc...). It's not going to happen for Skyrim. They're already too far into development, but really the system needs reworking. Fatigue needs to play a more integral role, and it needs to be more natural and thought-invoking, and a separate system, hardcoe only, needs to be put in place for sleep as well.
And yes, adrenaline can outweigh the effects of fatigue for a time, but fatigue in combat is still going to have a big impact, adrenaline or not. Many people don't understand how certain situations can push us to our limits, but on the other hand, you seem to be overestimating it to think that adrenaline turns you into the energizer bunny. In a combat where both parties are under the effects of adrenaline and are experiencing the same sort of thing, the adrenaline basically cancels out leveling the playing field. Adrenaline is more for man vs environment or getting out of a tight situation, not turning the tides in a fight to the death.