They did increase the amount of exp leveling dungeons offer.
And even without that: No, they dont need a nerf. Specially no in the form of lowering anyones HP - because THAT would have a negative impact, excatly the one that PotD already has: if mobs dont have high enough HP and die to fast, no one can properly learn their rotation and how to play their class. PotD mob are currently often dying before anyone was able to decently finish a full rotation. And not everyone is going to practice at a dummy to learn how to play their class at level 60/70.

Can we please stop asking for an already easy process in an easy game to get further nerfed?