Republicans need to be as far away as they can from this issue by 2016
In two years, Gay marriage will be the law of the land. Continued fighting by Republicans will stamp them as an archaic party fighting to preserve past hatreds
This is going to be interesting. Strategically, you're absolutely right. Republicans need to stop polishing this turd as it only serves to highight the distinction between what the majority of the electorate believes and what republicans believe.
However....
...this is a pet issue of the religious right. And as Huckabee demonstrates with his threats, its entirely possible for this issue to cause some serious discord among the GOP. I mean, more discord, given the clefting the party has already endured between mainstream and tea party republicans. So....more internal bickering among the GOP. And more damage to the brand outside it as support for gay marriage bans continues.
Its a lose-lose-lose scenario for republicans.