I have no problem with polygamy. What I have a problem with is how polygamy plays out in the real world. Polygamist colonies tend to be isolationist which leads to
de facto violations of civil liberties. Women often feel trapped, and they are threatened with physical violence if they leave. Young girls are often married off shortly after puberty. Young men are kicked out of the colony to fend for themselves. Also, wives are not allowed to have jobs so their children are often on public assistance. Polygamy, as it is practiced, leads to a very poor social structure.
I am torn on the issue. On one hand I am all for allowing consenting adults to enter into any kind of relationship that they want to enter into. It's their business, and it is a free country. On the other hand, with polygamy as it is practiced consent is often given under duress, be it social pressure or "brain washing".
If polygamy went "mainstream" it would certainly be interesting.