Man, I am *NOT* making my point about marriage.
I'd argue that "marriage" is less likely to be "looked at differently than shacking up" today. And you've got to remember that a reasonable argument to be made for state interest in marriage was the regulation of reproduction (else why the Rubella test that most states required?). What I am saying is that there is NO INTRINSIC VALUE in marriage to society. To the people involved in the marriage, perhaps. But no value to society as a whole. At least not from the State's perspective. The only value, again from the State's perspective, is that marriage (up until recently at least) usually resulted in children. Indeed, the very existence of a Rubella test requirement for a marriage license demonstrates clearly that the State expected a marriage to result in children. Equally clearly, the creation of a new generation is a *good thing* for the state, heck, it is necessary to the State's survival that children are born into the State.
I don't know how long ago you argued with Ben, but I agree that historically "shacking up" was frowned upon, but marriage was seen as a pillar upon which society was built. Our laws were developed when this notion was widely held. But those laws were not directed at marriage for its own sake - rather they were directed at the unit which produced a new generation. That happened to be marriage.
I'd disagree with Ben today if he held that the stigma associated with "shacking up" was as strong today as it was 20 or 30 years ago. I got married in 1983. At that time, if you chose to have children out-of-wedlock, there was a stigma attached to your children that they did not deserve. Hence, the logical thing to do if you intended to have children was to get married. I don't think that reason today is compelling because I don't think there is any stigma attached to children born out of wedlock anymore. In short, there is precious little reason to get married in our society anymore. But, that isn't the discussion we're having. The discussion we're having (and concluding the wrong things entirely imo) is whether the continued existence of legal benefits based upon marital status are appropriate. Since same-sex marriage has been approved *as the equal in societal value* to heterosexual marriage, I do not believe *any* benefits based upon marriage alone should accrue to anyone.