I've noticed several times when higher levelled players come into lower level areas and simply one-shot tough enemies, I've done it myself running through a delve in Auridon. For me this removes the challenge of tough enemies, especially in group content like dolmens and public dungeons, or even when I'm facing a quest boss that gets taken down before I can tag it/reach the area.
Would people be open to a system that de-scales your character level based on the area you're in? It's something I've experienced in Guild Wars 2 and works well but I'd rather hear the opinions of other ESO players.