I saw a video the other day on the X-15 rocket plane. It turns out that North American had an "X-20" on the drawing board, a second generation X-15, that would have flown from the B-52 into orbit. They cancelled it in favor of rockets, because the development time was shorter that way.
If we'd had cheap, reusable X-20 class aircraft by say, 1967, all of us would have had the opportunity to fly in space by now.
Even the shuttle was supposed to be much more reusable than it is. The booster was to have been a "Fly back" design. As it is, they "waste" an external tank every time they fly, and the SRBs of course have to be replaced/refilled, depending on whether they recover them or not. This goes back to Nixon era budget cutting, and keeping developement, as opposed to operating, costs low.
Robert Strange McNamara also cancled the USAF Manned Orbiting Laboratory and Dyna Soar programs. MOL would have had a skylab like capability years sooner, while Dyna Soar would have been a resusable fly back orbiter. (the Dyna Soar orbiter was featured in a SciFI movie (Marooned?) with Ted Jansen of "The Fujitive" fame)
Scrimping during developement hardly ever turns out to be a "good thing", but managers and politicians keep on doing it because it means you can have more messed up programs, rather than fewer good ones.