Yeah, thats alot of words to say that you feel entitled to afk for extended periods of time in encounters because of "muh immersion". Every combat focussed game ever can be boiled down to your avatar/group/units being supposed to decrease the life points of your opposition to 0, which is done through damage. So damage in every single combat focussed game ever is basically the most efficent action you can commit to, as long as you can afford to do it without your avatar/group/units dying. Healing by the nature of it is purely reactive and will always be reactive and limited in its use, because there is always only so much damage you can heal without wasting time or ressources. Even in the original Final Fantasy, healers would dps if there is nothing to heal because anything else would be just the waste of a turn. Their dps options were just limited to physical attacks up until you get holy, which usually is a late level spell. But from that point on, yeah, Healers would dps as much as possible.
And actually, you are kind of wrong. Like, objectively, when it comes to the MMO-Genre. What you are describing is the oldschool way of MMO design and it was never that popular. In actuality, the MMO-Genre only blew up in popularity back when World of Warcraft introduced changes like actually allowing players to be able to reach max level through solo quests alone and having a high focus on challenging high end group content. Your vision of the MMO-Genre was just never that popular and by shticking to it, the genre itself would have remained a niche one indefinitely. FF14 followed the bad new trends set by World of Warcraft compared to the more oldschool formate of FF11 which focussed on a long, extended and group-focussed leveling grind over challenging endgame content and guess what, its more popular than FF11 was at its best day.
Also, what else is there to implement but gameplay content? Like, what do you expect, that SE just dedicates patches to introduce new leveling dungeons?