It's been mentioned many times before that avoidable damage should punish people with damage down debuffs instead of vulnerability debuffs. Healers shouldn't have to work harder to heal because other people are bad. The group as a whole would have to carry the DPS output though. I do think healers across the board should get buffs specifically for GCD healing and things like Esuna. Let's say you cast Cure 2. You're next Glare should be worth twice the potency now. So Two Glares would be the same as Cure 2 and then one Glare. It's such a simple concept to make healers have GCD spells that are worth using by refunding the damage lost. That alone would go far to make healing more enjoyable if you knew helping people wasn't a sure way to hit enrage. Then lots of avoidable damage would feed into good healer gameplay.