In the case of prisons, abuse, Iraq, and reality TV, I think we learn that the reason scripted sit coms and regular TV programming is being displaced by Reality TV programming is, to put it simply, that Reality has taken over television.
It was the case there for a while that Television could manufacture reality. But the recording and distribution technologies (read: digital cameras and networks) have undermined television broadcast hegemony.
Neither broadcast nor cable TV could have thought up a scenario as sick as the one that has recently unfolded in Iraq prisons. In the hands of American soldiers, pornography is apparently not just for personal pleasure.