Yes, I suspect more people bought the book to rail against it than because they believed it. It is pointed that Murray's reputation peaked with the Bell Curve. Before then a lot of people gave his bullshit theories about the underclass more credit than they deserved. By embracing the racialised version of the underclass thesis, Murray went too far for a lot of his more liberal readers, and the critical reception was pretty hostile, as I remember it.
I, too, was one of those who ploughed through that unlovely tract to tease out it's apolgetic and racist logic, in a long review article for LM magazine.
(Listers can decide for themselves whether I fulfilled the free speech criterion of challenging prejudices rather than banning them at http://www.informinc.co.uk/LM/LM74/LM74_IQ.html )
When my editor asked me to give it the works we both thought that it would be an important milestone in the advance of racism. In retrospect I would say that it was a milestone that marked the exhaustion of social darwinism.
-- Jim heartfield