She's not hated nearly enough for being the shoehorned walking plot device forced into relevance.
>oh hey it's me, KAIDO'S SON (yes, somehow no one bothered mentioning Kaido's SON)
>oh hey, it's not actually a SON, but a COSPLAYING girl
>oh hey, she's LARPing as none other than ODEN HIMSELF, SO WE CAN EXTEND THE ODENWANKING AFTER THE FLASHBACK
>oh hey, I knew Ace -- you should totally let me sail with you guys!
>oh hey, I already know about Luffy and want to join so the author doesn't have to write an arc where I organically grow to trust the crew
>oh hey, the reason I did nothing for twenty years is because of these explosives shackles *deal with by luffy the next chapter they were introduced with zero struggle *
>oh hey, I really hate my dad -- he used to beat me up and stuff (literally a single speech bubble blablabla). I'll help you fight him, even though we literally just met and my existence was never hinted during the actually the alliance building part of the arc, very convenient!
Yamato is a shit fanfiction character and fuck whoever try to gaslight people calling it by claiming the only reason someone can dislike it is because of some silly powerlevel.