I hope the OP will not be upset with me jumping in. I will reply to to OP but also want to reply to this. No. Agreed. It does not. While one man-one woman model is obviously promoted, polygamy is not overtly condemned. Piling up wives, for a king, is advised against and proclaimed as something that is wickedness promoting (Deuteronomy 17:17). That's all I could find, in addition to what you wrote above.
I watched a documentary last year, where they interviewed various polygamous situations, including polyandry. For some reason men who want several wives (usually it's men who want it) almost without exception look like someone biting more than they can chew... There was however one case of polygamy from that documentary, which left a different impression on me. It was a polyandry story from Tibet.
The woman had three husbands. They had a son, and each man loved the child equally as if it were their own son. They were of peaceful demeanor, and simple people, and it looked like they lived in harmony. When asked by the reporter how did it come to having three husbands, she explained. In villages like hers, people are animal herders, and while the woman stays at home year round, the husband goes with the animals and actually spends a large chunk of the year far away from home. Cruel climate and wild animals combined, it is a tough life, and some women also lose their husbands, leaving them relatively helpless. She explains, this way, one of them is always there with me and my son during the year, keeping us safe. Polyandry is not unusual in that area because the climate and living are harsh. I could not imagine myself in such a family, but I really couldn't find it in me to condemn them. They seemed humble, honest and simple people, and this did not look to me at all like it was about lust or pride or greed. What I learned from this is that we often view Biblical polygamy and draw opinions and conclusions about it based on polygamy we see in
our age. Biblical polygamy probably looked something like this. It was another way of life, and the people were simpler, busy with surviving, different mentality. If it's a way to workaround a certain lifestyle (nomadic, animal husbandry etc), it might be adaptive and potentially not sin... Which is - I believe - the reason why it is not condemned in the Bible, but rather the optimal, perfect version of marriage - one man, one woman - is encouraged and reaffirmed. This was the answer I found and was finally satisfied with. Maybe it will be of use to somebody else because it's a difficult question that had me pondering about for years.
Now, is there a realistic NEED for polygamy for people living in the modern age? I really think not. And that's what changes how we look at it in modern age. If there is no need, as it is not adaptation in any way, then it's a WANT (cults and brainwashing are a separate category which I do not address here). If someone still insists on it, they are bound to have bad motives, wantonness, pride, name it. Again, this is my opinion, but I feel it pretty strongly. I am yet to see a couple (sorry: group) that lives a modern way of life in polygamy and not feel a "not good", if not outright
sick vibe from it. (Sorry if someone is offended...)
As to the OP, so I am not just a derailer with this post
yes
Yes, I believe that official marriage recognition is necessary - not a huge beach party, but it's about recognition, which is necessary. Biblically, I think we have the proof in:
Matthew 10:32 Whosoever therefore shall confess me before men, him will I confess also before my Father which is in heaven.
33 But whosoever shall deny me before men, him will I also deny before my Father which is in heaven.
We are in covenant with God. Marriage is also a covenant, which the Bible teaches is modeled exactly after Christ's covenant with humanity (church). This verse tells us that covenant must have full recognition of both sides to be valid. Witnesses are required. I'd argue based on this, that when people avoid to fully recognize their marriage before men, then this "marriage" is not valid at all by God's definition, and considered fornication.