Not sure if it's been mentioned yet (the thread is becoming kinda big ) : just to discuss another fail point of healer design : let's look at Limit Breaks.

While LB3 healer can feel good/rewarding and save a fight ; you need LB3 ready and a healer alive with most of the party dead (meaning it's likely due to avoidable damage).
Meanwhile tank/dps LB are involved in fight design themselves.

Healer LB 1 & 2 are never used. Why ? Because it's just an unneeded heal, and you're likely going to heal more with a single/couples spell/ability that doesn't lock you for 2s...