So what exactly do you want to do when there is no healing required?

If you want healing to be at a point where you're healing for a large majority of the fight, then you pretty much do just want healers to only heal. If you want there to be some level of downtime for recovery and optimization, then DPS should be more interesting in that period than Glaroillicosis + DoT and I have no idea why you would be against more DPS options.