Yes, I get your overall point. I would only add that you could not just willy-nilly throw out your wife on the street -- that would be considered as forcing the woman to enter "illicit" relationship, i.e. "to commit sin." You could "release" only a wife who was caught in flagrante. It seems to me that it is tied to the rules about polygamy which, in theory, should guarantee clear parenthood. That is, who are the biological mother and father who should take responsibility and care for, or claim ownership of, the child. (One man, many women - both parents are known; many men, one woman - fatherhood could be in question.) As for incest -- I don't know, perhaps at that time it seemed like a good idea (it is still part of some cultures), but genetics clearly shows that mixing various unrelated genes is healthy -- so, that's that.