You overthink it, and you basically give the answer here:
"I still walked through the game with a character capable of completing any objective for any guild, the difference being I spent more gold on Healing Potions than I previously had."
You can pause the game, and heal back to full. You can do this whenever, so how can you die. Even Diablo II had a system where a health pot made you regen, and was on a timer, creating a limit to how much damage you could absorb and forced you into playing the game.
How can you get all that you asked for, if they keep the favourite/healpot system?
This, if you have high health (high armor rating and magical resist also help) you can just pause, drink healing potions and continue, repeat as needed.
This is where Oblivion failed, at high level both you and enemies had lots of health while none did much damage, this made fights more boring than hard, yes you was able to kill the enemy at last, hard enemies just demanded more healing.
If anybody has played Oblivion without ever raising their stamina it become much more scary, same for Fallout 3.
Skyrim is better here as enemies can easy kill you at least if you have not boosted health on most level up and is armor capped.
Now add enemies past level 50 so you don't outlevel them,