Japanese comics have been made for boys and girls, and to be enjoyed by people of all ages for decades. American comics are usually aimed towards younger audiences and primarily male, or for a more specialized audience (geeks). Manga in Japan is treated the same way as books are here. There are books made specifically for young children, boys, girls, and adults, but even the stories made for young children can be enjoyed by older people. Understand?
Also, I assume you've been under a rock for the last, oh, 6 years or so, but anime and manga is huge in America. You can't fucking turn around without seeing shitty ass Inuyasha and all that fucking crap all over the place. It's cool to be Japanese in the United States, using chopsticks (even though you can't hold shit for more than two seconds) and eating sushi (though you hate it and most likely think it tastes like shit), wearing your goddamn kuroneko hats you got at the mall, carrying around stacks of manga, and pretending you speak Japanese and call yourself -chan.
Also, you aren't better than anyone else because you know how to get crap comics off the interweb.