What seems abnormal and outdated to us may seem modern and rational to them. I'm not condoning it, and the Afgan government should be advised to adopt a view geared towards equality, but it has been their culture for centuries through their religion, much like monogamy and equality has become part of western culture, through the spread of Christianity. Whilst many don't follow religion in the West now, some core values from it (such as monogamy and equality) have remained a cornerstone of our culture.