Why does the American media always demasculinize the blonde haired white man in contrast to brunette men?

I didn't know blonde men were demasculinized in the American media. What about Neil Patrick Harris, Brad Pitt, Matthew McConaghey(dity blonde sometimes :P), Paul Walker they have played womanizers on T.V. and movies. But maybe more dark haired guys play dominant characters because more women think they are sexier. I know a lot of girls like blonde guys but for some, tall DARK and handsome still rings true.