Here's a Jewish resource.
There are reasons for polygamy. God promises blessings on to the linage of the righteous man. Therefore, a blessing that is promised to a prophet will be passed down to their children and to the wives as well.
Therefore, God who sees past, present, and future, knows where He wants certain blessings to end up and with whom. So, He orders the prophet to take certain women to wife so that their children will bless many generations to come.
And it will have meaning in the next life as well. As it pertains to eternal marriage.
After the Lord's return, it will be practiced again among the righteous.
Isaiah 4
1 And in that day seven women shall take hold of one man, saying, We will eat our own bread, and wear our own apparel: only let us be called by thy name, to take away our reproach.
In the millennial period seven women will beg a single man to take on his name, in other words marry him. Their reproach is they are not married.
1 Cor 11
11 Nevertheless neither is the man without the woman, neither the woman without the man, in the Lord.
Paul's words are eternal. Everyone in the millennial period is "in the Lord", therefore they must be married... this explains Isaiah's prophesy.