What's the point with that quite lackluster story in Endwalker?

[Rulakir]

For starters there's a difference in treatment towards our character. Remember when I mentioned how she keeps calling us "my child", "my champion", "beloved children", etc.? And how she wouldn't address her peers back in ancient days the same way? She doesn't regard us as a fragment of the Azem who succeeded her in the Convocation. She addresses us in a very "maternal" way, like she thinks of us as her creation, rather than the Azem we once were. In fact when she grants her power to the crystal of Azem she speaks of "the crystal's original bearer". Maybe she speaks about the very first Azem, before herself and not about our former self, but keep in mind she never addresses us as the being we once were nor the seat we held, only about "the crystal we possess".

It's also interesting because in Ultima Thule Y'shtola comments about how Emet eventually came around to seeing the sundered as children, which seems to be just a step up from a familiar or an 'incomplete' being. It was progress for Emet, significantly less so for Hydaelyn who consistently views us that way.

The Azem crystal part is either an inconsistency or poorly written dialog. Emet created the crystal and is the only one who had it before the WoL.

She even contradicts herself back to back on the same cutscene. She first says "yeah Y'shtola, it's as you say, I sundered creation so you'd be better equipped to confront dynamis" and then IMMEDIATLY follows with "when confronting Zodiark he was too powerful so my only choice was to sunder creation to diminish his power." So, which is it?

It often seems like they threw every reason and the kitchen sink into why Venat sundered the world without notice or care of the elements that were contradictory. People are quick to point out that she made an effort to reason with her people in the post-Elpis cutscene, but if she was always going to sunder the world to make the Ancients able to interact with dynamis that means her outreach efforts were insincere. Otherwise, we have to accept that she believed the Ancients could have overcome Meteion without being sundered and thus it was not necessary.

As for Hermes, there's nothing to support him having brought dynamis to the table of the Convocation, so even if he were the only expert (which is also not supported) it wouldn't matter if that expertise wasn't a factor in the Final Days. The Watcher makes no mention of dynamis (and he should know), but he does the celestial currents. Elidibus later credits Fandaniel only with discovering the stagnation in said currents, noting that what we know at that point (before traveling to Elpis) is consistent with what the Convocation knew. He's not even remotely implied to be the architect of Zodiark so I don't know where people are getting that from, it's much more likely that was Lahabrea being the most specialized in complex creation magicks. What we do learn of Zodiark's construction is he was purposely aspected towards dark to encourage activity in those stagnant areas, nothing about dynamis.

[Lauront]

It's also interesting because in Ultima Thule Y'shtola comments about how Emet eventually came around to seeing the sundered as children, which seems to be just a step up from a familiar or an 'incomplete' being. It was progress for Emet, significantly less so for Hydaelyn who consistently views us that way.

Indeed, and his shift in perspective nevertheless does not move him to see the sundered as the same as his people, so much as a fragmented offshoot of mankind which has now proven itself in his eyes. With Emet, the fleeting mortality of his Garlean "son" is hinted at having taken its toll. I suspect he wanted to try relate to the sundered but kept realising they were not his people - the marked difference in lifespans alone would suffice for this - and eventually, having tired of all the bloodshed and struggle, and seeing an opportunity in Azem's sundered remnant, decided to put them to a test to settle it, which he ultimately honoured.

Point being? They only refer to "mankind" at various points because there is the same shared origin, but from the ancients'/Ascians' perspective (i.e. the original position) this is fragmented, i.e. sundered, i.e. something different, with some vestigial remains. Her constant reference to the sundered as children is similar to that of a higher being addressing its creations, from a vantage point where she has witnessed their actions for long enough to grasp that their nature differs from that of her own people, and IMO it is no accident she thus refers to herself as "last of my kind". I believe the reason Emet doesn't vocalise this is because he bore no such relation to them, but nonetheless his evaluation of their mentality and traits is of child-like beings to him, so they seem to share that viewpoint. It's all well and good for the ancients in Elpis to see some shared traits in you at a snapshot in time that put you above a regular familiar (but not quite the same as an ancient either), but it'd be quite another thing to 1) see their people transform this way and 2) observe these differences play out in practice over time. I believe this is also why you can choose in one of the sidequests to remark on them as either deities, not too different, or completely incomprehensible. To a mortal mind, the ancients are all of that at once because they share some traits with mortal humans but also possess others which distinguish them and result in quite a different type of being. Their views on death, for example, stem in part from their longevity and their relation to the star as a quasi-living organism which they revered, much like a dragon's perspective on time is affected by its immortality.

It often seems like they threw every reason and the kitchen sink into why Venat sundered the world without notice or care of the elements that were contradictory. People are quick to point out that she made an effort to reason with her people in the post-Elpis cutscene, but if she was always going to sunder the world to make the Ancients able to interact with dynamis that means her outreach efforts were insincere. Otherwise, we have to accept that she believed the Ancients could have overcome Meteion without being sundered and thus it was not necessary.

As for Hermes, there's nothing to support him having brought dynamis to the table of the Convocation, so even if he were the only expert (which is also not supported) it wouldn't matter if that expertise wasn't a factor in the Final Days. The Watcher makes no mention of dynamis (and he should know), but he does the celestial currents. Elidibus later credits Fandaniel only with discovering the stagnation in said currents, noting that what we know at that point (before traveling to Elpis) is consistent with what the Convocation knew. He's not even remotely implied to be the architect of Zodiark so I don't know where people are getting that from, it's much more likely that was Lahabrea being the most specialized in complex creation magicks. What we do learn of Zodiark's construction is he was purposely aspected towards dark to encourage activity in those stagnant areas, nothing about dynamis.

I suspect people insist on reading more in the lore at certain points than there is, is because if he was not strictly necessary, as that entire Watcher sequence very strongly suggests, her plan also no longer becomes the only available option. My own take is that it wasn't and that she simply committed to that path because of the vagaries of time travel to which she bound herself; at least, in the sense that they're keen on narrowing her available actions in that way to avoid an outcome such as creating an AU where things ended differently while also not making her come across as totally unreasonable... but IMO that comes at the expense of having to invoke time travel yet again in a very muddled way and constricting her agency.

[BaconBits]

The whole body swapping thing may have been a wasted opportunity, but I'll never get over Lalafell Zenos getting football tackled by a freshly revived Garlean corpse and the game taking it completely seriously.