Reality TV. it sounds cliche to blame them, but consider what the glut has done. Back in 1999-2002 when it was really big, it took up such a larger share of the programing hours that there were fewer scripted shows on air, even less actually survived passed a few seasons. It's probability, if only 20% of new shows (guessing) make it to the next season, fewer scripted new shows means fewer second season shows. Oddly enough, networks even started cancelling good shows like my name is earl and new adventures of old christine that did make it past the first season. This meant networks there weren't as any big shows to draw in people.