The problem of that is that healing is situational, if the fight needs little to no healing then all the intricacy goes to waste, same happens when a healer becomes good as we want to be efficient and that imply using the less resources possible, in other words, interacting with the healing kit less so once again the intricacy goes to waste. If the fight needs more healing is when that design could work but in order to make that consistent the game's damage would have to increase a lot, intimidating a lot of the newer and less experienced healers, something the devs doesnt want.
In the way the game currently works dps be it by buffs, interactions within the kit, cooldowns and such is the way to go as its the only way to have something that you can interact with consistently on any kind of content without increasing the hps requirements of the game on all the content
And then there is the whole problem of having all the healers play the same which shoudnt happen in any design but somehow devs think its ok