Without any official reason, my guess is that Zodiark was summoned while under the influence of Meteion, thus their fear twisted its form.
Or because the Ancients have different aesthetics and don't really view Zodiark's appearance as a negative, as seen by some of their creations.
At the end of the day, Zodiark was never in any position to care whether it gets credit, while we credited Hydaelyn due to our connection with her/Venat.I think the main problem though is that yes, we had an expansion show us that angelic figures dont mean benevolent or good yet we still only ever use light in the story, and the main angelic figure is still overall treated as benevolent and good with the demonic figure barely getting any credit for anything after its death.
Either way, I'm not sure that's something to be viewed as a problem, especially with respect to their appearances.
There is a difference between the physical and the philosophical concepts of light and dark.
I feel that's why people are confused because Shadowbringers only dealt with the former, not the latter. Light entities may be bad, and so are void entities, but shining your light over the darkness is still a good thing.
It doesn't matter whether you do something because someone says that you will or because you want to. It can even be both and you'll still have your agency as you're still the one who does the action.
The decisions she made was a result of Hermes's action and with the knowledge that we gave her.
We don't see her as a villain because we benefit from her actions. If she had allowed the Convocation to proceed, we would not have existed.
Our reality is indeed due to her, and since we're the hero of the story, the fact that we exist because of her and she is not going against us means that she would be treated as an ally even if we have to fight her in the end.