"gogogo" might make me quit this game.

[Absurdity]

Dungeons are easy by design. They have to be farm-friendly. People are going to be spamming dungeons for EXP. Leveling multiple jobs. Some will be spamming them for dailies (Expert dungeons). You don't want spammable content to be hard.

This is where I would have to disagree, they do not need to be easy, they just need to appropriately reward you for the time/effort invested. If dungeons were to become harder the simple solution is to increase the gains per dungeon. Difficult dungeons would reward you with more exp and more tomestones per dungeon, leading to basically the same amount of time invested but also less spam.