The good news is, you're right in that there isn't much gain and is a long-term drawback for the GOP to be doing this. But they can't seem to stop themselves. The party's in a crisis, in that the inexorable tide of demographics is slowly marginalizing a lot of their core cultural issues.

See the following article from 538:

http://www.fivethirtyeight.com/2010/06/emerging-republican-minority.html