This game is simply not made for reactive design anymore (if it has ever been in arr). Because of the long gcd you have to know and anticipate the fights, unlike wow and its shorter gcd which makes healing fast-paced and reactive. Off gcd are good in that regard and are enough most of the times.
So the biggest issue lies in our uses of gcds, which amounts to the same spell 99% of the time. We need more things to do with our gcds, be that support or dps. Scholar, albeit based on arcanist (so, an old ff14 design), was almost perfect from the get go in terms of engagement with its dots and aoes. Ast has its card system, which needs expanding, and whm took a step in the right direction with the blood lily.