The Reasoning behind The Sundering? (*6.0 Endwalker Spoilers*)

[Lurina]

It's because the Ascians were tempered by Zodiark. Emet-Selch admits to as much in Shadowbringers. And if you've played all of FFXIV current story you know that once a primal tempers you your choice of free will is gone. Your devoted heart and soul to the primal who tempered you. And Zodiark didn't want to talk to Hydaelin he wanted more Aether and more followers to grow stronger and sustain himself.

Zodiark wasn't a mindless primal hungry for Aether, he was Elidibus/Themis. A person. And I think you missed the part of his backstory in 5.3 where he specifically took a form outside of his primal body to talk to Venat and her followers.

Ultimately the Aumarotians chose to sacrifice people they deemed 'lesser' than themselves in order to sustain themselves and their 'paradise' forsaking the need to better the Star and instead better themselves.

As we find out on Mare Lamentorum, the souls of their love ones were literally trapped inside Zodiark - the ones who gave their lives to foster the creation of the new life on the planet in the first place. While I don't think anyone would act like they were doing something heroic, it's hardly a black and white situation.

[Jandor]

Zodiark wasn't a mindless primal hungry for Aether, he was Elidibus/Themis. A person. And I think you missed the part of his backstory in 5.3 where he specifically took a form outside of his primal body to talk to Venat and her followers.

It's possible to temper yourself if you make yourself into a primal.

With hindsight, making the guy in charge of reconciliation into the heart of Zodiark maybe wasn't the best idea, something like that is bound to make him a tad bias.