I think the exact opposite.

It's not that low level dungeons need a nerf - more that "end game" dungeons (ie level capped tomestone dungeons) need a rather large buff in difficulty.

If people's concern is that farming tomes will end up taking longer - then scale tome rewards up with the difficulty.

Over the past number of expert roulette cycles, the dungeons have progressively become easier and easier.
There are problems when you can easily pull every mob up until the next gate/wall and burn everything down at ease. Stuff should be quite a bit more threatening than they currently are.

That would fix the "Healers should DPS" argument. Make healing more intensive.