As a SCH main who started at the tail end of Stormblood, I only briefly got to experience the old SCH kit, and am mostly familiar with the current state of healers.

I still see a decent amount of meaningful decision making in my current SCH gameplay. For me, this comes from all the different healing options I have:
When the tank takes some damage I'll slap them with an Adlo because the shields will give some time for my fairy to top them up, but if it's a DPS, I'll probably just put a quick Physick on them since they probably wont take more damage for a while.
When the tank is taking continuous heavy hits, I have the choice of giving them Excog, giving me some time to do damage until it triggers, or I could do Fey Union to apply some powerful regen for a while, maybe coupled with an Adlo.
When there's some party-wide damage coming up, I can precast Succor and Sacred Soil to get some shields going, or I could use Fey Illumination and then Fey Blessing and maybe that will be enough.

I could keep going, but I think you get the point - there's still a ton of split-second decision making going on when I play healer. All healers have a large and intricate kit of spells that are all better or worse in different situations, and part of getting good as a healer player is learning when to use which spells.

That's not to say that I'm happy with the upcoming changes though. You might have noticed that I said all healers have a big kit of healing spells. Although I was using SCH-specific examples of decision making, almost all of them aren't far from the decisions you have to make as a AST or to a lesser extent, even WHM. There are only so many ways you can organize heals, shields, and some damage mitigation. To make up for this, the different healer jobs each have unique abilities that make them stand out from the rest, giving them a small niche of what they're best at. For AST, that's managing the randomness of the cards and the tactics of placing powerful buffs on the right people at the right time. For SCH, that's managing their fairy and manipulating shields. WHM is probably the most boring in this aspect, but has always retained their niche of managing their lily gauge to pull off some of the most powerful pure heals and in some cases high damage.
Over the past few expansions, I think squenix has slowly minimized the unique aspects of all the healers to make them more in line with each other - in other words, homogenized them. I think this trend continues with Endwalker, and I'm really disappointed to see it happen. AST gets de-emphasized cards and buffs, while SCH gets de-emphasized fairy pet management.