Maybe they are victims of their own success in TV and movies? What I mean is since there are so many other mediums in which to follow these characters adventures that the comic medium is becoming and outdated way in which to see them? Prior to becoming huge in movies and TV shows the only way you could follow your favorite hero was in comics
Now you can play through a comic on x-box. Or fight other comic characters on x-box. Or follow them in the movies or on a weekly tv show. Overall I dont think these characters have ever had the exposure they do now. Movies, weekly tv shows, animated shows and movies, video games. Comics are not as important to marketing and selling these guys as they once were.
I do think this weekly idea from DC could take off though. Combine it with online reading and weekly titles it could capture a market and anticipation almost like a weekly tv show.