America is practically founded on capitalism. How can you understand specialization & its benefits, and not see how marriage (well, used to) makes use of it?
Yes, if marriage was just about pretending "True Love is real, and the world is full of roses and daisies!" it would be a ridiculous sham. But as I have come to see it, it is more about facing the world as a "team". In larger groups (that is to say, extended family, all composed of marriage links), perhaps even as a "tribe"... think about that.
(Not to mention, kids are a thing we kind of need as a species, and I think most everyone is familiar with the plight of single parents)