When are we supposed to stop fighting?

[Theodric]

We are shown her pleading with people to learn to cope instead of bypassing suffering altogether in the post-Elpis cutscene, and they blatantly refused her and went for the Zodiark route instead.

Given that Venat is indirectly responsible for the Final Days occurring (given that she had foreknowledge of their existence due to the lack of a memory wipe) and then is ultimately responsible for the genocide of her own species? Nah, I don't think she was in much of a position to 'plead' with the very same people she actively sought to screw over first by withholding key information and then murdering down to the very last man, woman and child.

Zodiark was also a necessity by virtue of being the very force that served to prevent Etheirys from being destroyed. If not for Zodiark, there would be no Etheirys given that both the first and second set of sacrifices served to prevent the planet from decaying and dying altogether. That is, of course, in addition to Zodiark serving as a ward against the return of the Final Days in both the Unsundered and Sundered world.

Of course, had Venat spoken up about the Final Days before they happened then Zodiark would not have been needed but blaming the Ancients for mitigating a disaster that was sprung upon them without forewarning would strike me as utterly bizarre.