What this is really about is the determination of the networks to cut costs. Leno at 10:00 gave them a way to dump all the writers and performers necessary to put on a conventional drama or comedy. I think that they were willing to lose some viewers because they thought that an increasing profit margin would make up for it. It didn't and like JP said, the affiliates were going to mutiny. So Conan is gone and letterman is back at 11:35. But if the network programmers thought that we'd sit still for an hour at 10:00 every night showing bonobos at the National Zoo grooming one another, they'd put it on.