Starve the beast 2.0: the sick logic of a debt default
A default that raises interest rates makes it harder (or at least more expensive) for the government to borrow money. It doesn't take much imagination to connect these dots.
The actual movement small government types who really want an actually smaller government on the scale of before the New Deal really do think this would be a good idea: if you make it impossible for the government to borrow, it finally has to "go back" to what they imagine it was in 1920.
The Facebook walls of my conservative friends are my only data here, but I think this may be true. They are really willing to deal with a default because they think it's the "shock" that will finally "return America" to a pre-New Deal size government.
Norquist said that the deficits tax cuts would cause would eventually constrain spending. Even the most blinkard conservative (and I'm friends with several) has come to understand this is not the case. They may really see this as their only option.