The easiest point to make is that low level dungeons were never meant to be remotely difficult in the first place. Even in ARR, the penalty for not doing Orcatooth and Gyge's and Firemane's mechanics is inconveninece. You could heal through the adds if they spawn, or the party damage, and you have an absolute eternity before they do. Aside from possibly healers, I don't see a full skillset with reduced potency altering the already compromised "experience" of something like Sastasha or Halatali.

Balance starts to become more of a concern once you're approaching 45-50 and frankly there is no saving those dungeons. People walk through Praetorium and Wanderer's Palace and the like barely having to heal. Past 50, everything becomes much closer together so the extra skills can coexist more easily.