What does FFXIV lack?

[Shurrikhan]

Yes, thank you, I was trying to recall the exact details. It was parry/block that stopped working when struck behind. I liked this a lot. It asked tanks and parties to be mindful of positioning and orientation.

Same. (Aside, but... it was also far more caster-friendly, as tanks were then forced to stop spreading out mob groups by placing themselves in the center, haha.)

I disagree, I liked having to adjust my aggro <-> damage output balance depending on the situation.

Fair, and in that regard, I agree. I just think it was executed upon pretty horribly, to the point that 90% of the minutial optimizations were actually traps while only the overarching 10% to remain were actually indicative of good play in any situation not born of someone griefing, ignoring their kit, or ****ing up terribly.

Even accounting for those screw-ups, though, it's strategic depth was still just dropping into tank stance, say, after Goring Blade has been used and swapping back out just before the next or next-next one, give-or-take a Royal Authority actually being used as such instead of replaced with a redundant (Strength Down already applied) Rage of Halone to exploit the multiplicative Enmity modifiers based on how much you think your Dragoon will refuse to use Elusive, your StB Samurai Diversion, your BLM Lucid Dreaming, etc. and whether your co-tank overused their defensives and therefore one of your might die over a 20% difference in DR or adds were about to spawn (though then you'd be looking at Flash anyways, so... then it's more a matter of Goring drift, though the stances each cost a GCD themselves so a single Flash actually realigned rotation /shrug).

It had little meaning with WAR/DRK

I mean, it had meaning on DRK, in that it cost MP atop a GCD and that MP was much more relevant for DRK than for PLD (for whom it was only used for Clemency, itself often cancelled just to guarantee that Shelltron was consumed by the tankbuster instead of an auto-attack going off just before it).

I'm not speaking about Cure I / Cure II and freecure or whatever.

Okay, but then... nothing else came from resource scarcity. You just had a lower portion of incoming damage counterable by oGCDs, so that healing spells were a frequent part of casts (instead of just at-offensive-cost backup actions all sharing a common pseudo-CD, MP). (Yes, Flash cost a bit of MP, too, but you rarely wanted to rely on RNG misses for boss-fights, and it was your only AoE Enmity source, so... that was mostly just rote outside per the basic type of pull.)

That resource scarcity in turn gave varied priority to things like Cure I / Cure II because you could use Cure II to get enough healing out immediately to then reapply your DoTs on time (with, due to Cleric Stance, every offensive cast, at the time, requiring 2 GCDs if fed off of a heal [2s] or instant-cast, or just barely more if fed off a filler attack [2.5s] without Swiftcast), but in itself it merely made viable losing some offensive throughput now (or, in the next few GCDs) in favor of uptime later (by not going oom) by using a Cure I and maintaining Regen, etc., where they wouldn't interfere or force panic-heals out of your cohealer.

All else was just a matter of damage intake relative to "free" healing output. If you gave a boss an Amnesia aura, locking us out of our abilities, or just increased the number of damage events beyond what we could safely deal with via abilities alone, and you'd see the same results minus the ability for Bards to sacrifice their own damage to bail out healers' bad decisions or excessive rezzes (that instead indirectly falling to Paladins).

Most classes had to manage it.

That management was (A) avoid Skill/Spell Speed (a bit more SkS permissible if receiving Goad), (B) hit your Invigorate/Shroud/Luminous/Aetherflow on CD, and (C) bring a Bard and/or caster for Manashift. Out of that, only Manashift, Goad, and... hitting the CD on CD... were remotely "gameplay", especially once we reached Stormblood (wherein Bard/MCH just hit their MP/TP songs on CD in order to maintain raidbuffs and avoid pulling off the tank).

Dying literally drained this

It still does, and via job gauge elements, in a far more variably punishing manner.

a lot of the time when parties crashed back then especially in casual content, it was because of people running on fumes and unable to properly recover, and not just enough people failing to dodge a mechanic.

A party can still run itself out of the ability to rez just as much now as then, at least in terms of resources.

The difference is simply that we basically don't use healing spells anymore outside of the rare cast in Savage, and therefore rezzes are the only real MP costs beyond the net-positive churn of DoTs and filler attack spam. Granted, we also now don't have any real Mage's Ballad, Promoted Bishop Turret, Ewer, or Mana Shift to make up for party mistakes (all atop vuln stacks going from almost never seen to a part of virtually every mechanic, all to better ensure death and prevent healers from compensating significantly via ST healing spells instead of just rezzes).

The less efficient it was, the more it drained into resources, and I really, really enjoyed this.

...Again, though, this was only a thing at a party level.

Like, if you used a NIN, WHM, PLD, +1, and the Paladin took Ultimatum as one of their Role Actions, they could run into Bartam first pull with Shield Oath, Total Eclipse as not to burn Blind duration early, and then drop stance for extra damage as they have the WHM Swiftcast Holy, pop a Cure II and Benison via the Lily generated, prep another Holy timed to stun just as the previous one's elapses, then Ultimatum, Smokescreen, and Shadewalker together to let the Paladin hold threat as it Hallowed Grounds through 10s more, then cycle defensives (including Flash itself, worth a little over 20% DR against attacks capable of missing) and reapply Shield Oath if necessary to maintain threat until the end or a GCD or two away from it.

But even in that, while all the extra damage at the onset allowed the party not to run out of resources, it was still an optimal strategy regardless just for kill speed. You'd still do the exact same thing even if TP or MP hadn't existed simply because of how huge the relative value of CDs (damage multipliers, %DRs, and things like Divine Seal) were, favoring throughput right now over later sustain.

That's my issue with it. Whenever you played well, the other parts of the game made resources irrelevant anyways. It felt either vestigial or just a strange and very dull Speed-punishing tax... from inception.

I'm also talking about healer dungeon experience once you got AoE tools, and this has been taken away entirely from the game — and also what made me abandon healing completely after.

...I'm confused. Healers got their first AoE heal at level 10 (WHM/AST) or 35 (SCH), and their first AoE attacks at 50 (WHM), 52 (AST) or 30/35 (SCH). And what's been taken away among them? That, before level 30/50/52, a healer 'dealt AoE damage' (in a manner of speaking) only through increased healing onto a tank forgoing tank stance while having access to an AoE attack (i.e., until Stormblood, only if one had a non-PLD)? That sort of 'you and me and I am you' instinctive party coordination, since watered down by everyone having basically the same direct tools anyways?

That was the whole point, like tanks could balance damage and aggro

Again, because of the way tank stances worked (having tremendous cost to and very few viable transfer point for swapping until 4.1 Warrior), not really a tight balance there.

After level 40, a tank ideally opened in tank stance, swapped out early on, and never looked back. And in ARR, Paladins had no reason to leave Shield Oath in AoE, being better off instead just tab-targeting Rage of Halone itself (since only the potency, not the Enmity modifier, required combo progress) or the combo (whoever got Rage before gets Fast next) between Flashes as able to still keep up with AoE threat (as not to waste Blind duration and its mitigation).

Until HW, PLD effectively didn't even have any non-aggro skills [as, lacking Goring or Royal, Riot Blade was just a refill for Flash].

healers also had to balance damage and healing in accordance to their finite resources

Almost never according to finite resources unless they sacrificed the stat and LB bonus of bringing a Ranger or there were a lot of rezzes required. Outside of proximity to DoT replacement, priorities were stable; you just sometimes didn't have the MP to filler-attack and instead just idled.

People constantly telling me the game has always been the same are full of s***

It's definitely different now, aye... but a lot of what we had before ended up having an illusion of impact while actually changing the game not at all relative to what you'd optimally do even if those systems hadn't existed, outside of the aforementioned idling.

Now, if we could replace those pretenses with depth and make the kinds of coordination-requiring optimizations (beyond just "hit your 'Helps Party' button whenever it's available, cus that is just bloat) that early gameplay seemingly wanted us to leverage more prominent and noticeable to players, I'd be all for that. I'm just pointing out what all actually had impact.