And a big reason for that is regen/mana getting out of control such that raids CAN drop healers. Which is actually a reason to support this change.
It's not addressing the problem though which is why I'm against this change.
The problem is that healing spells are not balanced against the encounters. Why is their so little healing required that it can be accomplished by less healers? Or the converse argument is, why are the healing spells so powerful that they are able to keep up with the amount of damage being taken?
Regen is a part of this, obviously, but it's not the biggest factor. Regen is meant for maintaining healing over the course of a fight. If they are not able to challenge the innate regen of the player, then they are not forcing healers to utilize enough mana. I would argue that yes, they do need to change regen and I still have absolutely no clue why they still have so many regen abilities linked to mana, but the scaling of the mana pool is a flash in the pan to try to address that problem.
I think that triage healing is the proper course of action, but they need to make it actual triage healing. Currently, our healing spells are entirely too powerful. Realize that the damage of an encounter is based around what the healers can heal, not the other way around.
Say you were dealing with the burn phase of beth'tilac, between every big pulse you are essentially getting every single person back to full health. By the end, you start losing people because you can't get people back to full health fast enough. This is essentially triage healing, but the problem is with how the damage is coming in. Because we are able to get people back to full health so quickly, the damage has to scale to a point that we can't heal them back to a sustainable point. No amount of cooldowns or healing will be able to keep them alive regardless of the amount of mana you have available.
Now, if we apply a stronger form of triage healing to this same encounter, you end up with players taking more damage than can be directly healed from the beginning but instead of the damage scaling up constantly, it can scale up more slowly or even not at all. This means that you aren't healing people back to full between every pulse allowing you to reactively use throughput cooldowns to "catch up" as the fight progresses. This makes spell choices much more important because you can't just spam people back to full because you'll run out of mana in the long run. You have to heal up the lowest people and let the aoe heals and hots work as a sustainable healing.
The biggest difference is that ultimately in the stronger form of triage healing, you run out of mana and cooldowns rather than the later where you may or may not run out of mana, but the amount of throughput required becomes too high.