Nor are they any way as clear cut as you are trying to make out. It would push WHM single target reliable mitigation on tanks further ahead of both AST and SCH, and this would not be balanced. Adlo is rarely used to heal, its there to mitigate the next incoming attack, and this is how stoneskin is used in a fight by a competent whm.
Pro-shell (or whatever the whm protect trait used to be called) and granite skin can not be given back to whm unless they nerf other things in the whm skillset or seriously buff AST so it can compete for the main healer slot along with WHM.
Also, you need to address the fact that there are three healers in the game, and the capabilities of the healers have to be based around the three of them. As of yet you have failed to acknowledge that AST actually exists and how it impacts on the game balance between the three healers, including how WHM has to be balanced around AST's inclusion in the game.