I've always believed that gay people should be free to live the way they want and that they shouldn't have to ask anyone's permission to get married. I also believe that people should be free not to associate with them (or anybody else), if they'd prefer.
If everyone is required to think the same way, they you're not actually free. It seems though, that many people have a passionate desire to save bigots from their own bad business decisions, and would rather just give them their money blindly, without making the decision to shop elsewhere on their own. If businesses want to attempt to discriminate, in this day and age, then let them try and watch them go out of business. Prevent them from discriminating and all you're doing is saving them from themselves.