Imo dungeon design and the combat system are inexorably linked. If the battles are good and actually challenging and enjoyable it takes a lot of effort off the dungeon design and you can just focus on making dungeons that are interesting. If you have boring filler combat then you have to add a whole bunch of gimmicks to make the dungeon seem more interesting.

That and camera position. IMO having the third person camera has made it very difficult to make dungeons seem as interesting.