Great... now movie posters are sexist?

[Esquilax]

If people are trying to get their morality from movie posters, we have bigger problems

True, but by the same token, pop culture is what informs cultural norms. What you see on a movie poster shouldn't be the sole determiner of your morality, but it does become a component of the social mien you're surrounded by, which influences the way you deal with the world around you. We already accept that advertising can do that, it's why we place restrictions on cigarette ads, for example.