There's a profile of Miyazaki Hayao in the New Yorker of Jan. 17th.
The article isn't online (as far as I can tell) but there is a Q&A with the author, Margaret Talbot, who researched anime and Miyazaki on a United States-Japan Foundation Media Fellowship.
This part of the article resonated with me the most in terms of explaining why anime and manga are such a large part of Japanese media:
Are there countries other than Japan where animation is as popular across different age groups?
I think that Japan is unusual, if not unique, in its animation and comic-book culture. It's rich and developed there, and very respected as an art form. So you really do see people of all ages reading manga on the subway, for instance, and up to fifty per cent of book and magazine sales in Japan are of manga. There are ninety animated programs on television every week, and the genres are quite varied, from family dramas to violent cyber stuff to totally kawaii, or cute, kids' stuff. Anime fans here bristle at the idea that animation is just for children—though I think you'd have to concede that in the U.S. animation is more widely consumed by children than by adults. Miyazaki doesn't seem to have any problem with being perceived as a director who makes films primarily for children—he just thinks they should be sophisticated, good films in their own right.
The Animated Life [newyorker.com]
There's no doubt that manga is read by more adults here than in America but even so, ask 100 Japanese adults if they read manga and only like 15 will say yes, 12 men and 3 women. Ask them if they watch anime and it will be more like 5. 4 guys and 1 gal. I pulled those numbers out of my ass but that's my experience asking people I meet all the time.
In fact, just yesterday I went the speeddating thing and met 18 women. Only 1 watched anime and I didn't get the impression more than 2 of them read manga.