no one is blaming anyone, just pointing out as Spike Lee's movie "Bamboozled", almost prophesized,Let's keep in mind that Precious was written, directed and stared by black people. Like Tyler Perry WE are the ones choosing to show OURSELVES negatively, black people are supporting these negative images and then complaining that we are "being betrayed stereotypically."
Also black actors no longer HAVE to take the other roles you mentioned so who's fault is it they took those roles?
the corporate media will hype, award and give accolade to stereotipical images.
http://www.youtube.com/watch?v=C45g3YP7JOk