How can a society be just if it treats a group of people as commodities, little better than livestock? By your standards, we should embrace the caste system, female circumcision, and outright discrimination of individuals based on gender, coloring, sexuality, and socioeconomic status. Most of these practices are encouraged by religious tenets and are sanctioned if not encouraged. These practices do not further human dignity, they tear it apart and make women and minorities a second class of people.

And, this sexual acitivity outside of marriage that you say is "abhorrent to many people and has been for a long time" does not apply to men of these cultures, but solely to the women. Basically, in many of these nations, men can sleep with any human being they choose, provided that the person is not another man's "property". Many of these sexual practices don't conform to the heterosexual mold that you've stated is the basis for these nations morals, even though they'd love to present it this way.

Trying to advocate an that an individual of a free society not be treated as chattel is not a subversion of a culture. It is merely attempting to preserve the dignity of a human being.

Allowing pedophiles and murderers access to more victims is not the same as saying a cultural practice is unjust. Advocating fair treatment of all people is not breaking a law in a free society. If you want a nation based on theocracy, there are plenty to choose from in the Midde East. But a nation whose laws are supposed to be based on logic and fairness does not bend to a religious tenet that treats a group of people as slaves or worse.