...the more I think the Bushies used him as much and as badly as they used Colin Powell.  

In his pre-Iraq incarnation, Rumsfeld was known as a very smart guy with a combination of forward-thinking ideas and pragmatism.  

Yet along comes Iraq and we see a new incarnation: the driven dogmatist who doesn't want to hear about the post-maneuver phase of the conflict.

What I think happened is that Bush/Cheney put him in an impossible position, a double-bind, and he reacted accordingly.  We saw Rummy as being the source of bad strategy, but what we were seeing was only the visible face of something that came from above him.  

Think of it: the guy was too smart to have done this on his own.  But he hung in there out of loyalty and the desire to get the job done one way or the other.  And eventually it broke him.

This is completely consistent with the Bush/Cheney/Rove pattern of operation, where everyone else is disposable.