You gotta stop saying 'a complex DPS rotation', nobody is proposing 'a complex DPS rotation', just a 'more complex one than we already have'. Going from 1 inch off the ground to 2 inches is not a massive distance, but it's still an increase in altitude. Saying 'complex DPS rotation' calls to mind, for a lot of people, the likes of BLM, MNK optimizations, NIN's burst window, etc. And what most people suggest for healers, especially WHM, is still much simpler than new-SMN.
As for enrages, if the healer doing their rotation wrong (but still doing damage GCDs, eg just spamming Glare) causes a wipe in an EX trial, there's bigger issues at hand. Like, they're tuned to be clearable with like 6-8 deaths (assuming you don't get body-checked). And in Savage, there's plenty of lenience built into the enrage timer to factor in the fact that the healers will be GCD healing a lot more in week 1. I lost like 30 GCDs to GCD healing in my first clear of P11S, in week 1, and spent all but FOUR of my Aetherflow on healing. Still a clear. This 'people will wipe because they do their healer damage rotation wrong' angle purposely ignores that 'there is lenience to enrages already', or that 'potency difference between filler spell and new additions can be tuned to be low-punishment', etc. Though, given what SE did with Abyssos, I guess I can see why there'd be skepticism regarding SE's ability to balance things. But I am not about to go hamstringing my ideas of what WHM could get, because 'what if SE is really bad at balancing potency numbers'