I don't think we're ever going to arrive at a consensus on Hermes. Even if we collectively agreed that he was the one and only dynamis expert in all of Ancient society, there still isn't sufficient evidence his expertise played a part in the Final Days.
The post-Elpis 'Cliff Notes' version of the Final Days also left out a lot of crucial details. It doesn't help that it's from Venat's POV either, who is the character whose choices we're debating. It's an unfaithful retelling of events from a biased POV.
The Anyder cutscene in ShB makes little sense given the context of EW. Venat->Hydaelyn is more akin to Ysayle->Shiva than Elidibus->Zodiark. The person addressing her at the end made it sound like once she became the heart that would be the end of her, she also spoke as someone who was completely unaware of the sundering. The problem with that (aside from the implication Venat never confided her plans even to those she brought 'into the fold' to help create Hydaelyn) is either you believe Venat never intended to sunder the Ancients (which is a hard sell given that she would've been created with that ability) or she always intended to because if she didn't then the WoL's future wouldn't exist. One of the arguments I've seen presented here is that she couldn't do anything differently because she believed the WoL the best chance to defeat Meteion.
As for the rest, I just fundamentally disagree. I disagree with the premise that the Ancients were always doomed no matter what, I did not find the Ra-la world as 'proof' of that given they were fine until Meteion's meddling. Since that was the case for several of the worlds, I'm far more inclined to believe Meteion was the problem rather than their way of life. I disagree that the Ancients couldn't have come together in a crisis because they did. Whether or not you agree with Zodiark*, it was still an overwhelming collective effort on their part to stop an apocalypse, one which the sundered were unlikely to achieve.
* Speaking of which, I think the fact that the Final Days were warping their creation magics to conjure monstrosities that were killing them has been too easily brushed aside. I'm not comfortable judging anyone on their reaction to what could be the plot to a horror film. You do what you have to do to survive and anyone would jump at the first solution to making that situation stop.
So, what does that leave us with? Dynamis. This, in my opinion, is the true point of contention. Whether or not the Ancients could have ever found a way to deal with it. Ironically, Venat says, "Nothing is impossible. This, I have always believed." Yet, that seemingly didn't carry over into her feelings towards her own people's ability to change or figure out a way to defeat Meteion.
The rest is just pure speculation. We don't know that there were no blueprints of Meteion anywhere because nobody ever investigated Hermes and nobody knew to even look for such a thing. Incidentally, I suspect that Hythlodaeus was being very generous with Hermes about him not having submitted a concept yet because they were friends and he thought him trustworthy. We don't know that the Ancients themselves needed to face Meteion. Given that 75% of them were willing to sacrifice themselves to save the star, if asked some may have been willing to be sundered and trained to defeat her assuming that no one but Hermes was capable of creating a dynamis-based construct to do it. Plus, if Shinryu can make it to her, then so could another primal and Etheirys had plenty of aether to spare to work towards making that happen.
I could go on and on and I'm not looking for my ideas to be individually critiqued, that doesn't matter. What matters is that there were infinite possibilities and we only got to see the one that not only resulted in the Ancient civilization being destroyed, but 8 reflections of Etheirys in the process to get to where we are now. Personally, that's not a choice I would have or could have made. It doesn't make Venat compelling in a "she did what others could not" sort of way either, it makes me thoroughly dislike her because she never gave anyone a chance and her reasons for not doing so were just not good enough. Frankly, I don't think they ever could be when we're discussing the lives of billions of innocent people.
Lastly, I think allowing the WoL to express displeasure would've gone a long way. One of my biggest gripes is that after all this our characters are strong-armed into a 12k year 'full circle' bond with her, complete with emotional cutscenes and only positive, reaffirming dialog options, which did not sit well with me at all.