Current encounter design makes it impossible to make healers have to heal more in any interesting or nuanced way that is enjoyable. Higher healing difficulty is just pressing another OGCD button or spam GCD healing. Neither is interesting. The easiest route to make healers more engaging to play is with a DPS rotation, no matter how simple or complex it is.

Tanks have a DPS rotation, there's really no excuse as to why healers do not have one.