Anything's reusable if you throw as much resources into maintaining it as you would have rebuilding it every time. The Soviets just realized how stupid an idea that was. We didn't.
They did keep it around for the two things only it and shuttle could do: bring things back from orbit and execute single orbit missions (ie the cross-range ability to return to base after a single orbit.)
The Shuttle was a jobs program that has the side effect of going to space.