For example, I know a girl who is physically attracted to short guys and she gets criticizing and laughed at by other girls all the time. Same thing with me. I find larger women irresistibly attractive and people laugh and ridicule me for it. Furthermore, why do people laugh at those people who don't fit society's idea of "attractive"? God forbid if I ever marry a larger girl, may I be stoned and sent straight to hell!
Human selfish psychology at play. I guess the reason they're doing that is because ridiculing people who don't fit the norm is considered the norm. And if one person (you) goes out of line and actually just likes a person despite them not fitting that norm, these people will feel like you're calling them out on their bullshit. They don't want to feel like they're in the wrong (because they probably know that they are to an extent) so they ridicule you for stepping out of line.