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

[Lauront]

I wouldn't say his sadness was "self-indulgent". Grief is very much a thing that can mess people up. It never goes away, it stays with you for life.

I would say it is. He didn't realise many of his own fellow researchers shared his sentiments, implying he scarcely ever spoke to them to understand how they thought. It is not purely grief which animates him, but his inability to cope with the concept of life, terminating in death, which he cannot make sense of; he struggles to conceive of a purpose in this context. Moreover, it does not absolve him of condemning all existence to death, which he knew he was by allowing Endsinger to form her "nest" and shower everything in her path with her song of despair, including the creations he supposedly valued. He is willing to torment mankind both unsundered and sundered for his 'answer', still isn't satisfied in the process of getting it (as Amon) and still thinks mankind, both sundered and unsundered, is unworthy of living. His decisions are not purely in the heat of the moment, but calculated. To me this is all exceedingly self-indulgent and very much driven by spite.

And as we saw from Elpis, most if not almost all ancients do not grieve.

You should replay those scenes, too. We are shown, emphatically, that they even possessed funeral rites for their living creations which were killed accidently. Where do you derive this notion from that they did not grieve, let alone to the tune of "most"? There is also a separate quest, dealing with a mentor and her mentee, making her peace with the decision of her mentor to pass on and be reborn. Nevermind Pandaemonium and Eric.

For all we know, Hermes was the first ancient to actually feel grief. And when everyone around you dismisses that grief out of hand time and again, it broken him down to his very soul. Yes, I agree what he did wasn't the right thing, but he wasn't in his right mind either.

Yeah, no, he wasn't the first. And not only that, but his fellow researchers indulged his requests. Perhaps a bit too much. He clearly wasn't in his right mind but not because only he felt emotions...