We lack ability to heal through heavy aoe damage situations when our healing targets are spread out. At the point where chain heal become a situational tool we should have got a tool silimar to CoH,PoH or WG. We got healing rain and spirit link totem instead . Tools that require ppl to stack. Again.
Although introduction of spirit link totem was a change for the good (because of the fact that we needed a cooldown) we don't excel at healing clusters, we're just good at it. Just as resto druids are. I presume this goes directly against the "bring player, not the class" blizzard's policy.