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

[EaraGrace]

The flower may not change all the time and only be affected by strong enough emotions. But what I'm saying is: the ancients are aware that the flower reacts to emotionS. Plural. In order to observe such a behavior it must have reacted to something else. Not just "default white - black when Hermes is brooding." They speak about changes in hue and vibrancy. They're describing a spectrum. How can they claim that if they only ever saw it change for 1 person and 1 emotional state?

We learn that tidbit from Hermes, when asking the other researchers all struggle to comprehend how Meteion even works. In fact we knew more about Dynamis and the flowers then they did.

And that's why I told you about "creative solutions". They didn't need to go and fight Meteion as we did. Dynamis is an energy. They could have chugged on that same dynamis and make her dry on it so she's less powerful (think of Eureka, for example, and how the original plan was to reverse the flow of aether so the primal was cut short of it until it was completely dry). They could use that energy to create something or power up something.

I guess I’m just a skeptic.

Or another idea: how about instead of making a shield around the planet they just went and make an aether prison encasing Meteion? Remember, dynamis gets drowned by aether because it's far weaker (Hermes says so himself). Sure, Meteion had a head start towards the end of the universe, but like I said, she's a mere pet project, made by Hermes alone in his spare time. A whole team seriously devoted to the study of dynamis could have come up with more efficient ways to use it and create better, more efficient entities and devices to catch up with her before she became too powerful or have exploited the fact that aether > dynamis anyway.

It’s only drowned out because aether is more common in Etheirys. Dynamis however is more common than aether and thus such a solution wouldn’t work. And any plan would have to contend with the inability to reach her. Remember, it took millennia for Hydaelyn to collect the Aether necessary to reach Ultima. Any plan would be facing her at that strength.