Um, so those of us with kids can just lump it? Is that it? And straight couples without kids shouldn't be allowed to get married? Is that it?
It is a recognition of social obligation by the probability of procreation.
I don't quite follow your first sentence. If you have kids you have obligations to the kids and to society (and to the other parent of the kids) and marriage is a way of exercising your obligations, and a way of demonstrating you will fulfill them.
Exactly...we have kids...we are gay couples...are we 2nd class citizens? Are our kids 2nd class citizens?
Whose kids?

Different strokes for different folks, they say. I am a straight Lady, who desires a straight relationship, but i am not going to point the finger at those who desire a different life-style. It's not my business!!!. I am not a Busy Body!!!. If they don't try to force their will up on me, then i am fine with it. I got friends, that ride on both sides of the fence. I am not racist or have any sexual discrimination, at all.