Klein makes a good argument for why all of the other arguments for marriage equality are extraneous:
There is one really good reason to support gay marriage: Marriage is a right — as the courts have said on numerous occasions — and it is discriminatory to relegate same-sex couples to the second-class status of civil unions rather than recognizing them as fully married. This right in no way tramples on the rights of others. And its effect on state economies is irrelevant.And I agree--to an extent.
But the simple fact is, that the movement for marriage equality needs these arguments. Why? Because they are more proof that marriage equality harms no one, and instead has far more benefits for society than harm.
The truth is, it should be enough to say, "These are the inalienable rights of human beings, and as such we demand them"--and people should respect that. But people won't.
We are driven by our own selfish needs and desires, and opponents of marriage equality will continue to use arguments against the economic benefits of marriage equality. It's wrong, but it's true.
And until they stop using those arguments--until they accept it--we will continue to need ammunition with which to meet them.