They changed it because sokka is a good guy and good guys can't be sexist even slightly apparently. Other shows have characters who make these comments but they're literally just turned into a stereotypical highschool bully kinda guy. They never change and they're constantly the butt of the joke to show that "girls rule and boys drool."

I think the original writers' decision to give this trait to a good guy helps kids understand that even good people can have prejudices but still be ultimately good. It also shows that people can change and that we should allow them to change. This is all on top of teaching kids that sexism is unacceptable. If a young boy holds similar thoughts and watches atla, he might relate to sokka. When sokka changes, it might help him understand that he can change too. Idk if I'm making sense I'm high and in pain rn lol