Though, irregardless of if priority was shifted from oGCD via nerfs or via encounter design, the overall outcome would be that people will think of it as a nerf.
Since, going from DPSing 80% of the time to DPSing like 40-60% of the time will be a loss of DPS no matter what the case is that is making you shift.
That said, if the issue against going towards more GCD healing is merely how "Slow" the gameplay would feel without oGCDs... Then the problem isn't even that big.
You don't need to remove oGCD's to promote GCD healing. You merely need to shift the power of oGCD vs GCD healing.
At the moment, oGCD reign supreme because they're MASSIVE heals that make GCD heals plain not necessary. It's not just Benediction that is doing ridiculous burst healing, but all oGCD heals.
If you reduced the power of oGCD's, you can still keep them in healers kits, just they can then become supplementary healing skills, rather than the primary source of healing output.
Much like how DPS jobs have their primary damage coming from GCD skills and oGCD skills are less powerful but get weaved in alongside their GCD skills during the small periods between ability usage and GCD resets.
This would actually let you make healers busier, since you can afford to reduce oGCD skills actual CD's so they can be used more frequently, when they're not healing for 50%+ of someone's life.
Essentially, turn oGCD's into something that you use to quickly top up someone who went critical HP to buy time for a GCD heal to replenish their health, or something you use after a GCD heal to get that extra burst of healing to for example, get a Warrior back from 1HP after a successful Holmgang.
Thus making optimal Healer play be about balancing usage of your entire kit. DPS GCD's, Healing GCD's and oGCD's.
Which can then be further played upon with encounter designs that focus less on singular large bursts of damage, but more frequent, random, damage spikes.