I don't know. It makes economic sense, insofar as it seems to tend to boost the local economies wherever it's legalized. It makes sense with regard to the social fabric, insofar as it institutionally encourages stability, monogamy, and normative social behavior in all long-term relationships, not just heterosexual ones. It makes emotional sense because gay Americans who aren't designated as second-class citizens through separate-but-equal marital laws are happier, more secure, more productive and more bonded to and responsible to the community at large. It makes more sense with regard to societal well-being because a marital institution which encourages more stable monogamous relationships creates more two-parent families into which children might be adopted or raised. And it makes moral sense, because it helps to ensure that a married gay citizen might still be covered by insurance when he or she loses a job, or that he or she can visit their loved one in the hospital, or that he or she can be more secure in survivors' rights when that loved one dies.