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

[Katoar]

...

First of all, moral values and morality are social constructs created by humans. Their primary goal is to ensure the survival and perseverance of humankind. Objectively speaking, once the self is removed from any situation nothing is good nor evil because no point of reference exists.

Needless to say, nothing about the social constructs is permanent or inherently true. As a result, we as humans of modern-day society can observe and study old civilizations and tribal communities that abided by moral values that had starking differences from ours.

In light of this, what you preserve as a villainous act is constructed by a world that does not exist in the game. Games cannot perfectly reconstruct our world and since characters are set in a fantasy universe, some of their decisions which are based on what is deemed to be logical and rational will inevitably misalign with in real-life moral values of some players.

The goal of Venat was to prevent the extinction of humankind through meaningless sacrifices to Zodiark. She succeeded by sundering the world. The Sundering is not an act of genocide. A Genocide leads to the absolute death and end of a certain group. The Ancients, although fragmented, continued their existence. Indisputably, some of the decisions made conflict with the moral values of the consumers of the story. However, this does not make them irrational, nor immoral in the game world.

The desire to depict Venat as a villain is driven by one's extreme reluctance to let go of what they perceive to be right.