I've said it a lot and I am sure people are sick of it but healers don't need a real DPS rotation what they need is to have support abilities rolled into their kit. That would make them more interesting to play and give them something to do with downtime between healing without turning them into more of a DPS job with heals just kind of added on to them. Support abilities are however incredibly hard to balance and can be difficult for players to optimize since they are an indirect way of contributing to the party. As it is though the only way to really enhance healer gameplay is to give them a whole DPS rotation and make them green DPS with healing abilities kind of sprinkled in their kit.