Being a casual player, I feel that I can't contribute much to the thread which hasn't already been stated before.
Healers are broken. Their gameplay revolves around pushing one button repeatedly. Their healing abilities and spells are redundant which exist mainly to fill our action bars. They could easily be trimmed to a handful.
In addition, tanks and damage dealers have gained so many buffs to their self sustain that healers often have little to heal. Not to mention that Square Enix is fixated on designing content focused on how well you can make a character dance through the mechanics which makes the GCD abilities of healers almost useless.
It all needs fixed and all we are getting is silence. It's not looking good for healers.