I honestly just think Healers need more responsibilities and Urgency.
Healers should add Deeps when they can, but they should Ultimately be focused on Healing. The game just needs more time for Healers to be..yknow, Healers.
We also wouldn't be having these "Healers aren't needed" instances, if Tanks wernt designed to self-sustain to pretty much pick up the healers slack.