The issue with dungeons isn't just a "numbers" issue.
Their layout is uninspired, they basically all follow the formula of 2-3 trash packs placed in straight corridors, then some kind of barrier that prevents progress, another 2 trash packs in a straight corridor, then a boss, rinse and repeat. Sure, they may look fancy the first time you're in there but that's basically all these dungeons amount to for a long time now.
On top of that the trash is usually just as boring, most of the time they just do physical or magical auto attacks with maybe an easily avoidable aoe in-between.
This makes it incredibly easy to speedrun the dungeons since navigation is simply a one-way street, but it doesn't make for a very engaging experience.