Consider it this way:
Let's say 6.0 lands, and Reaper has had a complete rework again for release.
It's now got a single GCD nuke and a GCD instant 30 second dot from the word go, a 2 minute self haste buff at level 30, a 30 second instant oGCD at 56, and finally a big nuke that needs to be charged during downtime at 74.
That's it. That's it's entire kit to grind through solo MSQ content with.
SE would get torn a new hole to breath through if they dropped the class like that. And yet that's precisely what healers have been reduced to in solo content now. Watch a commentary free stream of a healer playing at level 10 or level 80 and the gameplay is far too similar. It truly boggles my mind that people consider this to be acceptable irrespective of what angle you are coming at this game. Giving healers a more compelling gameplay loop in downtime isn't a raider centric thing by any stretch. It's every bit as bad for the newer casual players, it's just that they haven't gotten bored of it yet (and ironically, healing levelling dungeons whilst being under geared is arguably the most enjoyable and challenging healing content pre Extreme and Savage).
It's lazy design from a team that has demonstrated that it is capable of so much more.
As far as the solution goes. Honestly, SE have backed themselves into a monumental corner at this stage and unless they've taken steps to address the potency of our healing kits vs our HP pools with this stat squish, I'm honestly not sure they'll ever dig themselves out of this mess until the inevitable overhaul towards the end of the game's life whenever that may be.
You are correct about the success though, I suspect that SE do indeed see the current overall strategy as being a net gain even if it does equate to having the core gameplay loop treading the same water since 3.4. The influx of new players handily outweighs the burnout of jaded veterans.