The space shuttle was not an improvement.
It was developed to service the space station, which was developed to give the shuttles something to do.
It is perfectly apparent, at least to me, that we aren’t going to do much of anything in space until we come up with a form of propulsion that isn’t rocket-based.
If we could control the gravitational force with 1% of the effectiveness with which we control the electromagnetic force, we’d be on our way. Anywhere.
A reusable spacecraft not an improvement over non-reusable ones, plus able to carry significant payloads? That’s a new one to me. Never mind the existence of the shuttle centering around the “space station” (unidentified), and apparently the shuttle work with the Hubble telescope has been forgotten.
If by non-rocket-based propulsion you mean something that will accelerate spacecraft beyond what a rocket is capable of, we seem to have a bunch of dead ends. Rockets will be the main way to get into earth orbit, though.