The Shuttle has always been this way. It's a high risk design. If they used a fraction of the money for W's Mars boondoggle, they could design a new launcher that would put the Orbiter at the top of the stack. The Orbiter could be used for many more years to come, safely, and then a replacement Orbiter could be designed to put on top of the same stack.
I’m quite capable of criticizing Bush, but the mere mention of his name in this context bothers me. This is a nineteen sixties or seventies design. Bush wasn’t responsible for any of this. And just because he set new goals, it doesn’t mean he suddenly becomes responsible for all the poor decisions made in the past.
It doesn’t make sense to me to completely redesign a launch system for a craft at the very end of it’s life expectancy.
It's all moot anyway. King Obama has defunded NASA. When all the income has been redistributed, then and only then can we established the first ACORN office on the Moon.
An alternate solution has always been available as well. To wit: A protective “fairing” of the exposed highly-critical carbon-carbon components, which would be jettisoned after transition thru the maximum stress portion of the flight.