I have another take. I call myself indepentant but am pretty liberal. I wish liberals would let up on this issue because it is a wedge issue that is really pretty minor. I know people who have nothing in common with conservatives, but vote Republican because of simple and easy to understand issues like this. If you are even slightly liberal you need to read "What's the Matter with Kansas".
I absolutely agree that it's one of those issues where the benefits are not worth the costs as far as the Democrats are concerned. It's another of those issues where the liberal position is nuanced and more difficult to understand than the conservative position, and these issues unfortunately are best avoided due to politics not being conducive to complex positions that can't be described in a quick sound bite.