The only reason why DPS is done more than actual healing these days is because of the abundance of oGCD heals. Back in ARR and HW when they were current content, we didn't have many oGCDs to heal with, so most of the healing was done with GCDs. Plus everything hit harder in those days. An example, you know how hard the first pulls of Holminster hit when ShB first came out? EVERYTHING hit that hard in ARR and HW, so healing was done quite a bit, with DPS being the "reward" for doing well. But nowadays there are so many oGCDs that DPS isn't a reward, it's the norm, because there just isn't a reason to use GCD heals.

Personally I'd like if the devs added a status ailment that hit healers that could "lock" oGCDs, forcing only GCD healing for a bit. That'd probably spice things up a bit and be a hell of a lot more fun for the healing community. Because let's face it, we healers are addicted to the frantic chaos of trying to keep people alive while everything is burning down around us (we're masochists like that).