The Shuttle is very inefficient at what it does. It should have been retired decades ago. In fact, it never should have been built.
America's original intent was to have a slow and steady manned space program with winged spacecraft being built first. The Soviets messed up all of that, politicians got heavily involved, and we've never gotten back on track.
The government likes to make big leaps that require a lot of money and time, which leaves us stuck with inferior systems for decades. In contrast the private sector likes to make small improvements with quick iterations.
As a matter of fact, it will be the private companies that will play a BIG ROLE in us getting back into space.