I don't really understand the OP. If you're a healer and you're only healing, how would that make the fight "impossible"? I can see how early on a few healers won't DPS while they learn just to be safe, go through it a few times before you see where the big damage is, and parts where dps is safer - at this early stage I don't think people should be pushing them to all-out dps either, everyone staying on their feet is optimal in brand new content, and in turn others learning are going to be taking more damage.

and yes, I miss the old notion of heals damaging undead, raise insta-killing them, and generally having fun with reflect