Savarel, I'm going to play devil's advocate and disagree.
Marriage is good for society. Not necessarily hetero marriage, but marriage itself. It provides a structure for families. When there are children involved, marriage is a legal framework to keep things more equal. Otherwise, you can have a woman who is a SAHM, gives up her career and retirement earning power in order to raise children, and there would be nothing to stop the man from up and leaving her with nothing after the children are grown. It's a protection. With marriage, the man would have to legally divorce her and give half his retirement account. Without, she's left with absolutely nothing.
Do I agree with getting religion out of civil marriage? Absolutely. But I feel that the spousal benefits are necessary to stable society.
You do understand that something like 50% of the children in this country are born to unmarried parents? Your notions are antiquated. I wish that wasnt true, but it is. Time to make laws to reflect reality, not the ideal.
As for the SAHM scenario, you might hate me for saying this, but a woman is more than capable of earning a living herself(or a man, if a SAHD). Once the children are grown and on their own, then the parents no longer each other anything.
There are plenty of households where both parents work. Its not impossible, and its not even that difficult. Alimony is also an antiquated notion.
In a more practical argument, you are again discriminating against an unmarried couple living together. Lets say one partner works at the Olive Garden to pay the bills while the other goes to the university, graduates, and then dumps his/her partner. Why is marriage specificly required to be compensated?