I was watching a discussion group on NASA TV on Thursday. At one point John Logsdon was lamenting that we let the Saturn 5 go, and he thought that was a big mistake. Another guy next to him said "Oh it was old technology when it was first launched and we really didn't need it any more.” The Russians are still launching their men on rockets that were designed in the 1950s, so what's wrong with that. The Delta 2s were originally from the old Thor missile, which was designed in the 50s and they still launch a large portion of our missions. We still fly B52s that were also designed in the 50s. If you have something that works, stick with it for a while.
There were other factors for the demise of the Saturn 5 than obsolescence. They would have needed missions for it to keep the production line going. But unfortunately after they canceled Apollo 18, 19, and 20, there was nothing in the pipe except for the Sky Lab. It was too big for any missions planed at that time and very expensive. If they had fully funded an aggressive space program that included a large space station, they could have used it to send up the pieces, and kept Apollo going to ferry the crews back and forth. Instead they built the shuttle, which sucked up all the money, and didn’t have a mission for it until they started the ISS in 1998.
A case of mismanagement and lack of leadership on the part of a lot of people, the president, congress, NASA, and ultimately us. The people were just not interested. Unfortunately, except for the celebration of the 40th anniversary of Apollo 11, most people hardly notice that we have a space program. They think it uses a much larger portion of the budget than it does, and want to cut it back or eliminate it altogether.