We're almost a year into the expansion, dungeons have been nerfed to cater to the casuals and noobs and lower number of players using them and in addition to that we overgear them... Go back to the launch of WOD when people were fresh and a lot of people were wiping like fuck in the dungeons because they were more than challenging enough without being challenge modes.

I tanked throughout the whole dungeon gearing phase and for a good while I had to min-max play all cooldowns and stuns and time active mitigation at a level of play that was far more hectic than most raiding, even resorting to kiting just to stay alive because those mobs hit me so hard.. It wasn't crazy difficult content by any means but my skill level as an experienced player (with a Mythic or previously heroic raiding history) is well above the average joe, and the same goes for the guildies and friends I was running them with. Those dungeons were really fun at the start and I felt they were balanced at the right place, but they don't need to be that hard now.

Mythic dungeons already provide a greater challenge (which ammounts to them just being the pre nerfed Heroics from Beta with numbers tuned) for those who need it and it can't be helped if you outgear them and still find them easy (which many do).