I think their intention ends up being a moot point when the result is undesirable because with the problems caused they can see that what they tried to do isn't working.
With your suggestion that their goal is to make things simple. This really only applies to the DPS side anyway, because although the healing requirement is low and that makes it easier for healers who have learned the role. If anything over time the healing aspect has a greater wall for learning because there's more abilities they need to learn to think about. Whereas, DPS is considered optional, when it comes to healing they would be more compelled to learn how to use each of their healing abilities. And to be fair, when the healing requirement is greater and you get to use the healing skills as intended, it's great design.
But when I used to help new healers back in ARR, if they wanted to learn Scholar, it'd be the more complicated of the two (versus WHM). I'd first teach them the foundations: Adloquium, Succor, Physick, Raise, Esuna/Leeches. They get used to that, then I'd teach them about Lustrate and Sacred Soil. After that, they could learn about faerie management, which is set and forget if you prefer AI, which was optional. Even then, micromanaging wasn't difficult, but the lowest priority to learn. And this was it.
Nowadays you have more on top of that. You have additional aetherflow skills and have to learn about using Exogitation vs Lustrate. Then you have your tactics - so Deployment Tactics and Emergency tactics as something else to think about. Working in Dissipation. Learning about Seraph and making use of her. And when to throw in Fey Blessing, Recitation and Fey Pact and how each of those can be useful. And at some point they'll have to learn that the GCD's that make up for their core heals no longer make up their core ability use but are secondary instead, because oGCD's after a certain level will start being much better use. To the point you'd probably remove Physick/Cure/Benefic from your hotbar entirely.
From a learning perspective, that's a lot more to think about. From an experienced perspective, it's bloat in most scenarios and therefore easy. But when you do get to properly use them? Yeah, it's great. The way they're designed to work and flow with each other is well suited to a higher healing requirement (which is another reason why I feel there's a desire for more healing). And in a higher healing requirement scenario, it too would be fine for stripped back DPS because chances are you'll be weaving them not spamming them. I told somebody the other week looking to get into healing to not be overwhelmed by the what each ability done, but start small with the foundations.
So if "simple" is their goal, sure the DPS is dead simple. I think the healing aspect has grown more complicated whilst being easier once you have your head around them. Sure you could argue that the simplification of DPS abilities to make room for a more comprehensive healing kit, this would only work or make sense with a higher healing requirement where you can make proper use of them.
If you're looking just at down time and healing requirement, then yes, one could conclude it's about making things simple. When you look at the actual healing kit, you've got something too comprehensive for the low healing requirement we've got. So I am not convinced that the "reason" is to do with simplicity. I am more convinced it is to do with a greater healing emphasis, which is something I've already addressed. I think what's more likely is that they've put a lower emphasis on DPS use and gradually built a more extensive and comprehensive healing kit, but balanced it around Savage/EX content.