Conservatives don't like the 'Big Tent' idea, because they believe that the fiscal conservatives will work against them. In some cases, they're right, but not always. Since the social issues wax and wane with the voting public, it makes sense to retain the fiscal conservatism, and those who espouse it, in the party, so voters consider it a more 'balanced' party.
We can talk about how we only want pure social conservatives in the Republican Party, but we are don't have enough in numbers to swing elections, so we have to have the fiscal conservatives, and some of the Independents, join us. That won't happen if we run everyone else off.
All that being said, we don't have to change the principles of the Party, even though the media would have us think we should. Polls show that folks want the Republicans to be the party of low taxes, smaller government, pro-life, and pro-family, since they vote for those who espouse those issues. Unfortunately, the Republicans in Congress, over the last 10 years, or so, spent like drunken sailors, and larded up the Federal Government, so folks gravitated away from them, even though they still held on the social issues. Because the health of the economy is such an important issue right now, the conservative fiscal positions will be more important to most voters, but we need to cultivate candidates who while not as solid on the social issues as the fiscal ones, won't actively work against us on those social issues.
I have to agree that the core of the party remains fiscal. But social conservatives make up a vast and increasing part of the party, and are turned off by the very social issues surrounding Sarah. Many people, including myself strongly support tradtional marriage, abstinence until marriage, free from drug use, against homosexuality.
Personally, Sarah was enthusiastic and seems to have conservative values. I know you are not going to agree, but social conservatives are a larger base of the party, while the core is mostly fiscal.