I think polygamy will become legal for completely unrelated reasons. Women are more and more educated, make more money, but still only marry up. There simply won’t be enough men for women to marry up to. Why any man would subject himself to multiple divorces at the same time, but whatever floats your boat.
We’ve had thousands of years of literature about squabbles in monogamous marriages - are they bad also? Maybe that was the most accurate part of the Bible.