It wouldn't be a problem if all healing in content was like how it was at ARR and HW when they were current content, where a healer had to prioritize healing, and being able to DPS was a reward. Back in those days we took a LOT of damage from everything, and if the healer wasn't good, or if the tank couldn't hold aggro, that was it. If they brought back the damage level to how it was when 2.x and 3.x were current content, I don't think you'd ever see another complaint about healers being boring. The only reason they're boring now is simply because of how easy it is to heal up the damage.