Because that's not what the movie is at all. It actually spends a fair amount of time mocking consumerism and hating on the negative impact barbie has had on women's self image and feminism.
It's actually pretty crass with a lot of offcolor jokes. It's more targeted to adults who had Barbies as kids during on the 80s/90s.
Oppenheimer forces the viewer to strongly consider the awful thing that was done those two days.
I'm as critical of the US as anyone I've met but your take is bizarrely ignorant to what they were trying to do. I feel like you'd have to be intentionally missing the point to come away thinking that movie was pro-america in any way.