Green DPS is an entirely viable concept, if they actually committed to it. Nowhere does it say that healers need to abide by the oldschool mmo design of "spend every second healing or someone dies".
What we have right now is healers with a toolkit designed for massive amounts of healing, but the content design for green DPS which never utilizes said toolkit. This just doesn't work, it leaves both the players who want to struggle to keep their party alive and the people who want to be a combat medic unsatisfied. The only ones happy with it are the people who engage with the job at the most surface level possible.