I've been considering the strictly biological aspect between men and women related to children. The command to be fruitful and multiply is limited by biology in men from roughly 15 to 90 years of age, about 75 years. In women the age range is roughly 15 to 50, about 35 years and less than half the man's window. Could it be that Yah's intent was for the man to keep fathering children until he is no longer able, and when his first wife is no longer able to conceive, he is allowed, and expected, to acquire another wife (while maintaining his covenant with his first wife) to continue his primary mission of being fruitful and multiplying? Is there any other reason to have double the window? In addition, if the church were to acknowledge the primary mission to be fruitful and multiply as long as each is able, I would think polygyny would be much easier to accept. Right now, it is the monogamous wife who biologically determines when to stop having children, contrary to my Biblical understanding.
On a side note I was told "I had my daughter, and now a son, so I'm done". I had no say in the matter. Biologically speaking, I should have continued having children for another 30 years, but I was cheated out of that opportunity, and with the son I did have, the world would be better off with more like him.
Whether it's because of rebellion, or biology, in my opinion, that is too much power to hold over his head. I believe what is a reasonable age is "when he is no longer able".