That is a great point. I'd only add that this "problem" goes much further back. This is the same socon demographic that voted for candidates like Pat Robertson in 1988. People forget that Robertson actually won some states in the primaries (even finished 2nd in the Iowa caucuses).
Social conservatives are a vital part of the Republican party and are absolutely right on many issues such as opposition to abortion and gay marriage, but because many socon's put most/all their focus on social/religious issues they often vote in the primaries for really terrible candidates who have absolutely no chance to win a general election. There is zero chance someone like Pat Robertson was going to be elected president - even in 1988, yet over a million social conservatives voted for him before he finally dropped out.
George W Bush is exactly who illustrates this. He was a Social Conservative, but a fiscal moderate, to big government spender. Add to that, a Big Labor Union advocate, and we have what a large number in this party see, as the best choice. No wonder we are snatching defeat from the jaws of victory.
Good point bringing up Robertson.