I just can repeat it again and again. Phys. range have a much easier life in any content and you can´t ignore that fact. You´ll never get interupt by anything that´s happening in the game, unless you missplay by yourself.
First... i doesn´t mean that DPS shouldn´t be a thing. But everyone but some hardcore players don´t come up like "ih bard, please don´t unless you give us 1%!". I´ve played with double phys. range or even double classes and we finished bossfights in random parties. It doesn´t matter that much. Either the boss is dead or not.
I could take your example and turn it the other way too. At the moment phys. range will be nearly even to melees or caster, you´ll see them everywhere and probably one 2 phys. range parties with melee + caster for that 1% buff. Just because it´s easier to play. The chances to beat the boss will significantly increase, just because the chance to die, to do a mistake, to get interupted, whatever is way lower on phys. range chars and the player.
Next to those facts, which are probably SE thoughts behind it, they follow a clear route how a raid party should looks like. You see it at the content and the stuff which is going to happen. 2 tanks + 2 melee + 1 phys. + 1 caster + 1 pure and 1 shield heal.
And you say it in the end again. "If a Melee/Caster can´t adapt, it´s on them.". And yes, that´s stuff SE is keeping in mind and it´s a minority of players who can do this pretty well. Here again, it´s way easier to learn the phys. range rotation and just play it down without any real stuff you´ve to adjust too. That´s why classes who has a "harder life" from beginning will do more damage if they´re played well.
I understand your point and i would be with you if the gap would be THAT issue, but it isn´t at the moment. 1-2k which is more player based and just a real thing when you look at the top players is still "ok". A bigger gap would be an issue or the moment when the range damage is not enough to beat the content. Imagine range get their 2-3k dps buff, so the content will adjusted to it and if a melee / caster isn´t able to play it perfectly down, you´ll fail. It just doesn´t make sense.
Overall more support and deeper game design is another thing. It´s definately welcome and if ranges finally have something real to care about, i wouldn´t mind if they do similar damage as melees. Sry to say that, but imo this is just an elitist fflogs farming issue to me than anything else. Players would´n´t even get the difference without it and specialized farming groups with RNG luck, uptime strats, whatever. But this is not part of the game and nothing SE cares about. The game is obviously build for midcore players / casuals and it´s more like SE expect players to do mistakes, to miss the uptime, whatever.
In kind of the classes, i would even say that the internal testers of SE are double-lefthanded anyway. Maybe they do even expect that every player plays with the given equipment instead of building on BIS gear, which could last in even damage numbers in their internal calculation. Who knows....
Try out monk if you want. It got dumb´d down, but the pressure on you in kind of rotation, positionals, adaption and hurry buttonsmash is still a thing to do good damage. I´m pretty sure the most won´t get decent dps numbers.