Largely, the major problem with this is the creation of redundant healing spells and combat encounter & job design that is wholly out of touch with each other like WHM from 3.0-5.0 (healing role design). It would be more interesting to design them to alter changes how the job heals or mitigates/nulls damage like, if hit: current remaing hp will be the difference between damage recieved and the player's max HP with a two second invincibility to help mitigate large pulls