The two reasons given for the sundering were she didn't believe the Ancients capable of changing their ways (an issue of hers which predates Zodiark) or of being able to interact with dynamis. Those reasons are mutually exclusive, so there was no situation we're presented with in which she wasn't going to sunder all of mankind. It's why the narrative surrounding her is problematic because her "trying" to get the Ancients to change doesn't mean anything if she still didn't think they could defeat Meteion.
(Quoting
Brinne because she said it better than I could.)
Venat, fundamentally, is an ideologue. Her sense of love and wonder is sincere and true, but she is a big-picture person in the extreme, who thinks in the abstract. When she says she loves, it’s not of any specific person or thing. It’s love of “humanity’s potential.” It’s love of “a flawed world,” of “mankind’s ability to find a way forward,” - a particular way of seeing the world that she believes only she, at this point, has, that she waxes poetic about in her big speech leading up to her question of her journey. Our Azem is quoted as describing her as "both close and incredibly distant," "akin to a force of nature," and that seems very apt. She also admits that she, like Hermes, is dissatisfied with the world order as it exists now – she wants others to see the world as she does. To welcome struggle and strife and flaws and therefore, in her eyes, truly treasure the “miracle of creation.”
Largely because of her interactions with us, the portrait she receives of someone from “a flawed world full of suffering,” Venat further romanticizes the idea of beauty and strength in the face of struggle and suffering. She sees that version of the world as more exciting, more appealing than the one she lives in now, which she sees as misguided and indolent – she already had, hence her being extremely receptive to hearing Meteion’s two-sentence description of the Plenty, and deciding the Ancients were on the same path based on that.