A couple of things that would go a long way to fixing the situation with dungeons;

People say "oh, SE can build multiple routes, but nobody will run them once the most efficient path is worked out."
Fine, don't give them the choice. You can have 3 routes through each zone which is randomly determined at the start. In turn, this can lead to alternative bosses.

Also, randomise enemies. I don't mean pull them from everywhere, but make each enemy area be able to pull from a predetermined set of enemies thematically appropriate for the dungeon. Might make you have to change your play style on the fly - maybe there' are more AoEs to deal with? Maybe this will have consequences with environmental hazzards like in Dzemeal Darkhold? Maybe there are more DOTs to remove?

None of this really gets close to open world, freedom of choice dungeons, and I accept that. But it does at least allow the content to live a little bit longer.