Unless i am wrong, that is actually a nerf so instead of trying and fix an issue that according to you had little to do with dmg and or the overall dificulty of the fight but more to do with not so good restarting mechanics.
The reason behind might be completely different but if the end result is basically a nerf to the instance, so while you might be competely right doesnt it change the fact that it made content easier by lowering/increasing the numbers, which it what is being argued not the reason. Even more so since its quite likely that the new content might get the nerf hammer, disregarding the reason, making it equally as easy as current content (heal wise), which goes agaisnt the idea that the new content will be more difficult to heal.
It would seem the devs have a track of taking the nerf route if content is hard and that might be a problem for the involvement of healers in said content. That is what i am trying to question here.