basically there should've been nothing wrong with healers being able to DPS, the problem is though, that DPS uptime available through design on most battles makes it "you either DPS and i am watching your logs, or you are bad healer, because you use GCD heals"
i mean, i started my MMORPG "career" since Lineage C3 got released. back then healers couldn't DPS at all. it was only thanks the possibility to wield any weapon healer classes had at least some chance to solo things. back then, healers abilities to DPS were wanted simply due to that.
But whatever the case, many people seem to enjoy healers as who have 80% uptime for DPS and come with various arguments why its better. I think we need a consensus. battle should be designed for at least 50\50 heal\dps ratio, then maybe everyone gets what they want