If we're going to use the descendants of polygamous relationships as a argument against polygamy, I think it falls apart pretty quickly.
Jacob took four wives, and for no particularly urgent reason. There is nothing in the Bible record about him to indicate God was displeased by his doing so.
Most obviously, our Lord and Savior (not Barack) could not have had the ancestry he did without polygamy. He was descended from David via two lines, by two different wives, with his legal (though not blood) relationship through the royal line via Bathsheba and Solomon, and his true blood relationship through another wife.
Kings in the Middle East had harems, at the time. That was just a fact of life, and the Israelite kings were no different.
My reading of it is that Jacob wanted one of them (Rachel) in particular, was tricked by his father-in-law Laban into marrying her sister (Leah) first, then each wife, exercising sibling rivalry expressed by proxy childbearing, urged him to take her maidservant as another wife as a means of producing children.
Therefore the foundation of the twelve tribes of Israel was through deception and rivalry, yet despite this God still brought good out of it.
There is no discussion of polygamy I've read that doesn't involve rivalry and bickering among the multiple wives. Each wife gets less than a whole husband.
Left to his own devices, I'm not sure Jacob wouldn't have been satisfied with Rachel alone. Jacob's favorite children (Joseph and Benjamin) were her sons.
"Neither shall he multiply wives" was a commandment to Israel's king.
Christ Himself pointed back to Adam and Eve's union (monogamous) as the divine blueprint for marriage. Anything beyond that was due to man's "hardness of heart" provision for which was given in Mosaic law.