people don't want their neighbors' sexual hang-ups forced on them. Americans do care about social issues. They just can't stomach the hypocrisy of using beatitudes as a wedge against beatitudes.
This guy in a Shea combox summarizes it well.
"the large core value of modern conservativsm and GOP politics seems to be a sort of “every man for himself” social Darwinism. As an orthodox Catholic, I cannot support that. On the other hand, what ought to be the core value of liberalism (“we’re all in this together”) very much fits with orthodox Catholicism — except that nearly all modern liberals have tossed this out the window. If every citizen has an inherent value that must be defended, one could never justify abortion."