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

[Caurcas]

Remove man's ability to strive and to struggle and you remove the ability to understand life and its importance. Brutal and harsh? Maybe, but necessary.

[Brinne]

Remove man's ability to strive and to struggle and you remove the ability to understand life and its importance. Brutal and harsh? Maybe, but necessary.

Nah, I don't think so.

[Kyohei]

The sundered do not understand life and its importance more than the ancients. One just needs to see every expansions and wars that fuel them, or how eorzeans treat beast tribes.
Ancients actually valued life enough to sacrifice themselves as fuel to save their star and life on it. If we talk about how they had a procedure to end creations, that wasn't something they were happy about as we can see in side quests. The creators are sad for their creations if they have to be cancelled, so they do value them. Also, the process of deciding whether a creation gets to stay or not is driven with life quality of said creation and the ecosystem it will evolve in in mind. Hardly something one considers if they don't value or understand living.
The only one who thinks ancients don't value life enough is Hermes, but that is only because he refused to accept death as a whole. He refused to accept the death of his mentor, and can't accept the death of creations that would suffer and make other creations suffer if they weren't terminated. Ultimately this inability to welcome death as part of life leads him to nihilistic thoughts.

It's a very weak and reductive argument to write off the ancients as equal to Ra-la civilisation.
No one could predict how the ancient civilisation would have evolved if Venat had shared all the knowledge she had. Actually, no one can decently predict how a civilisation as a whole will evolve, if they'll die out or thrive. It's possible to assumptions based on past and present elements, make statistics, but there is no definite way to predict the future.