thb as a comparatively new player, I love it when I got higher level dungeon in roulette. It's less boring with all the skills I have, and some dungeon mechanics.
I think it would be great if dungeons at high level (something like 71+?) are more challenging.

Now I'm still stuck in ARR content so not sure of 5.0+, but from time to time I still see healer/tank struggle to keep up with their roles :/
So yeah, challenging dungeons should exist more, but should be in another cat for roulette