NASA's idea for a space station and what Congress actually approved were two COMPLETELY different things.
What was the NASA's original idea for a space station? You mean the slight reduction of space from Space Station Freedom to the final ISS?
Freedom to ISS was no "slight" reduction, not by a longshot. On the other hand, Freedom was itself a reduction from NASA's plan for an orbital spacedock that would be able to refurbish and refuel orbiting spacecraft as a first stage to an orbital infrastructure system. The idea was (at the time) that the space hangar would be used to assemble, piece by piece, a larger spacecraft that could function as a mobile exploration platform for long-term voyages to the moon or to Mars in any configuration you wanted. Critics came to deride this plan as the now infamous "Battlestar Galactica plan." Ironically, in retrospect it probably would have been cheaper than continuing the shuttle program through 2010.
Easy: they don't CARE about their capabilities, problems, or needs. Space flight is a pork-barrel project in congress: they don't care if the rockets even work, just as long as somebody in their congressional district is being paid to build them.
I thought as much. It seems obvious that NASA isn't what most of us think it is as far as administrations go.
The problem is, NASA is exactly what most of us think it is. The reason this is a problem is because what NASA thinks about itself is vastly less important than what CONGRESS thinks it is.
It comes down to this: Orion and the SLS do not fit NASA's needs for space exploration. It is not designed to explore space, it is not designed to save money, it is not designed to go to the space station. It is designed to keep contractors and space technology infrastructure in key congressional districts in business; it is designed to give the workforce at KSC something to do, whether or not that something has anything at all to do with a meaningful space program.
The Senate knows this, and they want NASA to lie about it; NASA refuses to lie about it, and the Senate is pissed.