Social conservatism does not have to mean executing abortionists or locking up people suspected of homosexual behavior. Certainly it would be a big achievement if the govt simply stopped *promoting* such behavior ($ for planned parenthood, special gay rights such as marriage) but there is a lot the govt can do without being coercive or expansionist. If the govt can put out an ad campaign to encourage people to join the Army or discourage drugs, it should also encourage better, perhaps private education or discourage abortion. It all falls under the ‘power’ of the bully pulpit; the govt should be able to use the modern media.
And what makes you think it does not?
Frankly, I'm sick to death of PSAs promoting everything from the Peace Corps to "buckle up." And with 0bama in the White House, it's only going to get worse, I'm afraid.
The government promoting morality is (borrowing from Penn Jillette's analogy) like a slaughterhouse pushing vegetarianism. You don't need to ask why.