Quote:
Y'shtola: Having seen mankind brought to the very precipice of extinction, you wished for us to develop a means to overcome despair.
Y'shtola: You believed we had the potential, and sundered all creation to see it fulfilled. To deliver us to that swirling maelstrom of dynamis in which our foe hides, and grant us the power to defeat her once and for all. Is this not true?
Hydaelyn: It is as thou sayest. 'Twas the trial to which I subjected mankind, and it hath led to untold bloodshed and suffering. There was no kindness nor justice in the tragedy I wrought.
Hydaelyn: When confronted with the almighty Zodiark, my only recourse was to rend Him and the world asunder, that His power be diminished for a time.
Hydaelyn: And so it came to pass. Now you, my chosen, have surpassed my expectations. Surpassed me.
So, yeah - she's explicit in regards to it being her goal, which Yoshi confirms in the previously and repeatedly linked Q&A in addition to her fears about her people eventually becoming like the Nibirun. Zodiark was needed to maintain Etheirys' shield and had to be Sundered because he was an obstacle to Venat's plan and while she could not fully control the scope, Zodiark's power was so great she ended up having to sunder all life in addition to him, but that's collateral damage as the Ancients are very clearly stated to be the main target.
Quote:
Hermes: Harboring high concentrations of aether, we ancients cannot readily manipulate dynamis─nor be manipulated by it. Therefore, rather than our selves, the calamity affected our magicks.
Hermes: In contrast, having been sundered, the people of the future are composed of but a fraction of our aether.
Hermes: Thus are they susceptible to the influence of dynamis─and its transformative potential.
So it was very much a deliberate act and an intended consequence. The Sundering was always about replacing her own species with something different in an effort to bring about Meteion's defeat. A combination of action and inaction resulted in a heavy cost and it strikes me as rather strange to downplay and ignore that cost to try and frame it as something completely different.