This is an interesting topic for some reason to me, and have spent to much time thinking about it instead of doing more productive stuff. Just some thought after reading the thread over a few days and mulling over a few things for another few.
I could be wrong but it seems that there are a fair number of people that think polygamy wouldn’t lead to an imbalance in the number of available women as others claim, and cite the current poly community as evidence among other things. I guess I just don’t see how it’s relevant how a select (and small?) group act, is in any way indicative of how the rest of the country would act and practice polygamy if we snapped our fingers and it was now legal.
The big twist is that we are not an overtly male dominated society as others that have/do practice polygamy are, so it’s not an obvious imbalance as well as a twist we don’t have a lot of data points on.
In short I find it hard to believe that their wouldn’t be more MFF then FMM marriages. I do think the overwhelming majority will be monogamy though.
I don’t have any studies or such to back this up but it’s what I believe. Men (or a good portion anyway) all else being equal (i know this is never the case) would resist sharing a women with other men. I believe its fairly high up and near the top of our “priory list”.
I don’t think it’s as high for women. I think security ($), family and the ability to raise said family, is much higher. I think when presented with a choice of marry Guy A be the only wife and work full time while raising you children, or Guy B be the second wife and you can work part time or not at all while raising your child, some when will choose B. More so than men, in my opinion. I don’t think it will be a lot, but i also don’t think it will be uncommon either. I know it’s not as simple as those two choices but for some i think it will be.
In summary though I think their will be poor, less well off men who will find it hard to find a mate because some of the men at the top will collect multiple wives and why not if you can have a trophy wife, why not two? A trophy husband seems to be a lot less common. I guess I just don’t see how it would be any other way, I know some people point to the poly community or more choices for women but I guess i don’t see it as balancing out what I see as humane nature.
To address the OP. In short I think it, polygamy should remain illegal. While it dose no harm on an individual level that I can see, on a society level I see harm, and no benefit at all to society to out way that harm. I believe it would leave a shortage (probably slight but still real) of available women to marry. This is actually the reverse of the opinion that I came to the thread with.