It's just Oda doing a bad job of hyping Oden up all over again.
Personally I can't understand how seeing someone's execution and reading his diary can make someone behave like that. I meant sure, she can admire him but not to the point of identifying herself with the dead person in question. It's just shit really, Oda should really remove Oden's curse on the series asap.
And like you said, it's just sad when one think about Kaido's position. His only child admires one of his worst enemies to the point of no return. That is just the one of the worst things that can happen to a parent.
On top of that, going as far as posing and identifying as Oden meaning Yamato wishes to the same things as Oden which leads to the question, if Kaido didn't put bombs on Yamato as restrains or if Kaido is in her league power wise, how would Yamato behave? Would she simply leaves Wano, letting her father terrorizes the land of the person she's considered herself to be? Or would she continue Oden's quest of slaying Kaido, her father, to be perfectly in role of her character?
Either way, the character of Yamato would be a total mess of conflict ideas and a failure of a character in One Piece's world where everyone fights to be able to be themself, for their own dreams.
Imo, Yamato shouldn't admire anyone. Her own quest should be to find her own self amidst this mess of black and white, power and compassion, not to just cosplaying and not having her own definite character.
Kaido has it a lot worse than Big Mom as a parent since at least the later's children are somewhar content being her family.