healers worked in gw2 because of class variants and healing choices. Placing a healing spray as scientist or healing bomb mixed with a weapon of choice (dolphin shotgun for me) made it awesome.
Healing while burning enemies as a sunflower made it awesome for me
as far as BFN goes, I see zombies having the upperhand in many cases, but not in healing. The scientist is just a chore to play with landing the sticky heal and chasing moving targets with the healing hose. Yet I feel like making zombie healing easier would just help zombies who really don't need buffs. People would hate me for saying, but reducing zombie defense and making scientist easier to heal with would feel about right, but also bump up the demand for scientists in groups and I know people don't want to be forced to play something they don't want to play so it's a mixed bag