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

[Heroman3003]

I feel a touch reluctant to call exchanging the lives of ill-defined lifeforms to spare the souls of those who gave themselves to save the world from languishing in purgatory "evil" without deeper context.

The Ascians crossed a line once their plan shifted to involve the lives of sundered mankind, but if we're talking strictly animals and other non-sentient life, they (And mankind as a whole regardless of the era or fiction vs. reality) were already okay with using those beings for their own benefit. In the end, it wasn't even the morality behind the decision that was being opposed but the ideology.

As far as Azem goes, all the evidence suggests that the former instance was simply a case of putting emotions before logic and reason as it's discussed that they had tried several alternatives, exhausted avenues of approach and that Zodiark was an absolute last resort because nothing else was working.

Its very ambigous as to what matter of life they would be sacrificing. We know they treat familiars, who we know are perfectly capable of being completely independant and sapient living beings, as little different from animals already. And we know that primals hunger for richer aether and more of it. While it is very much an assumption, I would not say its a stretch they would populate the world with not just life, but sapient beings that they view as lesser, part of another sacrifice. And even if they didn't, ultimately, they'd still basically be abandoning everything they as civilization stood for prior to the Final Days, while very much wreaking great long-term havoc on star's aetherial state to return the paradise lost. I do believe that summoning Zodiark was a 'pragmatically correct choice', although game's morality fits not around pragmatically, but emotionally correct choices. However, after he prevented the Final Days and restored world to livable state, that should have been the end of it. And if it was, I do think that Hydaelyn would never be summoned and sundering would never have occured. The Ancients would start working on building new paradise, perhaps with brand new appreciation of individual lives imprinted upon them now and forevermore.