Boondoggles are seldom mistakes.. they were done on purpose..
Some of it was done to show how earth-centered space use could be, and to ease pressure from a growing green movement that wanted the space program's $$ to fund their research.
Some of it happened because Nasa was too focused on hurrying up to the moon.
Some of the problems were because it was a Cold War project, at least at first.
Green concerns hurt more than one thing. There was the freon in the tank foam. There is always problems if anyone thinks to use nuclear power on satellites or talk about it in connection to human flight.
And the truth is, getting out the the gravity well is expensive. And hard. And unless they find better ways than sitting on the top of a long controlled explosion, it's going to stay that way.