Can I draw a parallel from what the French gov't is doing to how the US gov't forced the Mormon church to abandon their practice of polygamy? Would that also be a case of the dominant culture trying to oppress a minority culture?
That raises the question of why the government is sticking its nose in marriage to begin with.
Practically? I think its tax related. The tax code is fucked up as it is. I can't fathom coming up with different tax codes for man who wants to marry anywhere between 1 and many wives. (or one wive and many husbands)
But are you raising the point just for the sake of argument or are you actually for polygamy?

Well, a legal relationship like marriage is not (or not merely) an expressive act. It's often said that there are three parties to a marriage--and the third is the state. Since marriage is the state's recognition of a relationship, that makes sense.

Yes, I'm the big bad evil nazi I guess. Let me go buy some jackboots and run around yelling 'sieg heil.'