Stepping Backwards

[privateer296]

While the neccessity of having a untilitarian launc vehicle seems obvious it's troubling that the program seems to be taking a step backwards. The Shuttle is expensive to run but its design is an antique. I cannot fathom why NASA would not want to learn from the Shuttle and progress forward with a new more efficient design. I understand that cost is a significant factor but shouldn't a redesigned orbiter be able to cut costs by implementing design features that would make it more efficient...Is this just a matter of cost or am I missing the big picture when it comes to the future of shuttle programs?