A few thoughts.
Regardless of whether it is in the state’s interest to recognize, promote & incentivize marriage, it is undoubtedly in society’s interest.
Children do better with two parents. This can be possibly be gender-neutral-- but we definitely know that two parents are best, and biologically, the easiest route to two parents is the same one we’ve followed for quite a few million years.
Women do better when married. Single motherhood is a blight on society. It may be a tragedy, it may be a choice, but economically and culturally, it is a feedback-loop disaster for children raised in these environments.
Society does better with married, i.e. unavailable men. Crime rates are lower, illegitimacy rates are lower, economic performance is more equitable across socio-economic strata.
Want to see poverty in the Western world? Single parents raising children. Want to see lack of education in the Western world? Single parents raising children. Want to see high crime rates in the Western world? Single parents raising children. Again, and again, and again-- society’s greatest ills can be found at the foot of broken marriages (or marriages that never happen to begin with).
Now, I do not believe that it’s the fault of people trying to redefine marriage to include them in the definition. “The Gays” aren’t destroying marriage-- heterosexuals have done that just fine, thank you very much. “No fault” divorce is the most obvious reason. Yes, it’s terrible and surely immoral to keep an abusive marriage together for any reason, even “for the children”-- but those few instances where “no fault” divorce fixed that problem also opened the floodgates for anyone to get divorced, no matter what the reason. And once the cultural sanctity & integrity of the institution was damaged, the cracks allowed all sorts of corruption.
Bottom line: marriage has NEVER been about love. It sanctified an economic arrangement to ensure the most stable child-rearing environment-- and simultaneously, get males off the competitive marketplace for women (i.e., there’s still a huge benefit to heterosexual marriage even when no children are produced-- those are now men who are not off fathering illegitimate children with multiple women, and a stronger economic unit is formed in a marriage).
We used to live in a culture where marriage was easy, but divorce was hard. Now we live in one where marriage is hard-- insofar as everyone thinks it’s a much bigger step than they used to think, so they wait for it-- but divorce is easy. That’s a new place for us all.
IMHO, the answer to marriage-- or, more accurately, establishing enduring and stable two-parent families-- is NOT to define away the institution for heterosexual couples. The legal benefits of marriage, the “contractual” stuff-- perhaps there’s a good reason to apply that to other parties. I don’t see how extending, say, hospital visitation rights and insurance benefits to homosexual couples hurts anyone.
That said, anyone looking to expand marriage must first find a way to salvage marriage. It’s not about love-- any two people can fall in love. It’s literally about the children, folks, and giving them an environment far more stable than “Let’s get divorced tomorrow” or “We’re breaking up, who takes Timmy & Sally?”
I don’t know how we turn the clock back here. It’s probably too late-- we’ve all grown more secular (nobody quite fears God like they used to), and we all live in a selfish culture that says our own individual happiness, however defined, is the most important thing in the whole wide world.
Maybe the answer is as simple as this: if gay people want to get married so much, fine, let them have it. . . the rest of us ruined it anyway, you’re only getting useless garbage now.