What is imbalanced about the healers. I keep seeing this said everywhere.

[Gemina]

The way I see it, is balance comes from a few things. It comes from each job having established its own identity. Each of them have clear advantages over the other, but also have disadvantages that the other healers do not. This makes each healer unique, and they compliment one another when paired together. An example of this is SCH has powerful shields, but cannot apply a steady regen to the raid. They have Whispering dawn, but it is ogcd that can only be used when it is off of cooldown. WHM however can keep up Regen all day long, but does not have any shields outside of Divine Benison. However, DB is single target only and like SCH's WD, it is a ogcd that is only available when it is off cooldown. This is balanced. Put them together and one can shield the group while the other gives them heals over time (HoT). Again, this is just a small example.

Healers are currently unbalanced because of AST. WHM has no advantages over AST; it can do everything WHM can do, but can also buff the raid with their cards. On top of that, their DPS is also higher, has more mobility than WHM, and they can also shield the group if they happen to be paired up with a WHM. Sure, WHM can get the job done in all content, but why even have one there when you can have an AST? The end result is only one optimal healer composition, which is SCH/AST.

In order to balance our healers WHM needs to have a clear advantage over SCH and AST outside of a healing requirement. But the devs are adamant about keeping WHM a non-gimmick type of "pure healer", but this doesn't work and passive abilities like SoTL are negligible at best. So the devs are in this limbo-like state because if they rework and over-tune WHM and/or nerf one of the other two healers, all that is going to happen is it leapfrogs over AST or SCH in the optimal set up.

Some things they can do to give them this advantage is increase their DPS so SCH and AST can't compete, they can give them the ability the reduce enmity for DPS and themselves, reflect back damage that tanks take, or even give them the power to remove weakness from KOs and raise players w/o weakness. These are distinct advantages that doesn't involve healing, shields, or HoTs. We'll just have to see what they come up with though.