It was designed so that it could be launched from the US into a polar orbit, capture a soviet spy satellite, and land back to the US on the next orbit. This is why it has those enormous and heavy wings.
The shuttle-derived vehicles made a lot more sense. The shuttle could be used to ferry crew and modules for building space stations, but those two goals would be better served by two different types of spacecraft. It could return large objects from space and that was the one role where its unique abilities would shine, but that was never done.
NASA could have made continuous improvements to the heat shields, engines and other expendables to make flights cheaper, but never had the budget for it.
The shuttle-derived vehicles made a lot more sense. The shuttle could be used to ferry crew and modules for building space stations, but those two goals would be better served by two different types of spacecraft. It could return large objects from space and that was the one role where its unique abilities would shine, but that was never done.
NASA could have made continuous improvements to the heat shields, engines and other expendables to make flights cheaper, but never had the budget for it.