Well said opinion, but the thing is, i could take all your written stuff and put it in another point of view.
The biggest issue is the static rotation and like 0 tolerance to play around a lot of mechanics. Away from "how poor" a lot of mechanics have become, if 1 guy fails, it´s mostly a wipe. There are a lot of missed opportunities for different classes to keep the ball rolling or just no time for those smart over 9000 reactions.
Positionals on that side bring atleast something to do, to take care about in such static fights. Some ppl seems to like "staying still and playing 123", but tbh... gameplay-wise it´s just straight up boring. It might work in other games, but the mechanics there are not so obvious, those games are not that forgivable with just 1 rezz for the whole fight and not 100 rezzes / LB3. You don´t even have a 100% rotation, you´ve priorities, a faster GCD and even DD´s are able to tank a boss for a while with defensives and aggro ping pong etc... Healers have take care about mana, because any boss hits harder. Tanks have to swap or kite multiple times and need to manage the adds and multiple debuffs, etc... Those games are way more innovative than FF14.
Let´s say we would get ride of positionals for whatever reason. What do we get? Mudra? How innovative is it in the end, when you use combination X at the pull, combination Y when you´ve to leave the boss for 2s? It´s unique, but not deep or anything else. It´s part of your rotation and you may adjust with it to any boss mechanics. Otherwise 99,9% of all NIN´s stuck behind the boss and playing 123.
A job gauge? Press button X in your rotation when it´s filled?
You do nothing else than learning and playing down your rotation. Even phys. range with a bunch of proccs are like "1,2,1,2,1,2 oh procc,3, 1,2,1,2". Healers might be the only one with "a real impact" in kind of gameplay, because a good healer will always take care about other mistakes, maybe even use rescue.
That said, you can´t really bring something "deep" a lot of ppl talk about. In the end, it´s just pressing a button at moment X, thx to the given rotation. Positionals might have the same effect once you got used to them, but you still do more and might adjust to tank missplays.
Imagine the game would be build up more on skills like "rescue" and with multiple add-mechanics with kiting or "DPS-tanks", casts you´ve to interupt, more debuffs, more damage on the tanks, more mana issues and so on. But no... it gets even less, so all players do simple "spread & stack" mechanics and perform their rotation without the need or even the chance to adapt in some way.
And tbh... the reason, why positionals have such a low impact in potency or other stuff, is the casualization. SE wants pretty much everyone to clear everything but ultimate / the last tier fight. This means we´ve ONLY 4 fights every ~2 years a lot of players will never beat and in case of ultimate it´s a lot about "no time" instead of "no skill".
The current potencies allow the players to play 99,9% of all content in the game completely braindead. The additional potencies are just there, to give some extra % in damage to improve for those who want. Making them more rewarding would last in more cries from the casuals than the crying about the whole existence of positionals right now.
I can just speak for myself, but i can repeat it again and again... positionals are fine and way deeper than any other "class-mechanics" in this static rotation game. If someone really feels rewarded, because he played the rotation well or pressed button X because a job gauge or whatever got filled, maybe even because he did more damage thx to a class buff or better gear, then i don´t know... I would call a big GG! to someone who saved a run with his decision-making and given class tools, but not to someone who fulfilled his job in learning a rotation at a dummy after watching several class / bossguides.