Personally, I feel like each healer should have a button or few more to manage offensively, Lucid Dreaming removed in favor of generally reduced MP costs (400->250 or so), significant MP costs on their healing abilities and/or less oGCD healing throughput and should be able to do even a good 75% of a DPS's damage if allowed full offensive uptime. I just also think that forgoing
all GCD healing for said 100% offensive uptime shouldn't be the norm, even in simple dungeons.
Tanks, likewise, should probably have Tank Mastery stripped from them, with enemy tankbuster damage reduced to compensate and tanks' maximum offensive potency increased to ~70% of a DPS's in compensation.