What you see here on the forum, and what you see in the game, are two completely different worlds.
You'd think, reading these forums, that everyone playing this game is extremely skilled, and the dungeons are too easy.
Then you log into the game, do a roulette, and the tank doesn't know what a cooldown is, the healer hard-casts Cure I, and the DPS stand in the bad.

Dungeons are part of the story, and as long as that's the case, they can't be harder.
For balance, not the extremely skilled elite, made up of forum posters, but the actual player community in game is relevant.