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

[Brinne]

I don't fundamentally disagree with your overall assessment of Hermes's actions, and that they were cowardly and despicable. However, in terms of premeditated intent, the scale of potential consequence is something to consider. The concern of most of the creations on Elpis is to prevent damage to the Star through harming its ecosystems. A potential apocalypse didn't seem to be on the mental table for most of them. Someone who removes the brakes on their car is not going to anticipate that, through a series of absolute freak circumstances, the removal of those brakes is going to go as far as blowing up their entire city and/or destroying the world.

Ishikawa, in Famitsu, also made the point that because how drastically wrong Meteion's search for answers went was without precedent - so was much of Hermes's existential angst in general - so of course Hermes's attempts to reconcile them was, well, messy, to say to the least. (I would say a lot more than that, but nonetheless.) There are implications that Ancient society was built off of what was once an "untamed wilderness," but if any disaster of this scale was ever possible, it was apparently so far enough in the past that it doesn't warrant real consideration these days. One doesn't anticipate removing the safety fixtures on their car as prompting another round of the mythological Great Flood - though of course, they're accountable for deciding in that moment when realizing that's somehow what's happened, out of spite and depression "yeah, screw you guys, bring on the flood!"

So, yes, on the broader scale, it's incompetence rather than active malice. He black and white, in the text, did not anticipate this outcome and was genuinely shocked that it happened - then his need to lash out overrode everything else because Emet-Selch made him mad. It's fine if you don't draw a distinction between the two after a certain point, but I also think it's fine if some do, when Venat was fully aware that the city was going to blow up for, presumably, at least years, and seemed to see its destruction as for the greater good, actually. Some people will even find it specifically repulsive to have violence inflicted on them by someone who insists they are doing it out of "love" and "for their own good," far more than someone who is clearly doing it out of malice and spite.

I completely understand your wariness of this becoming an echo chamber or being ruled by mob anger against a character who is still a charismatic woman - and I sometimes have similar concerns - but I don't think it's unreasonable for people to have a range of valid different personal responses regarding one's takes on the culpability regarding the Final Days and Sundering re: Hermes and Venat, both for in-universe reasons and narrative framing reasons.