Although I personally don't agree with polygamy, I don't see a problem with it as long as all participants are over the age of consent and capable of clearly and knowledgably making a decision to take part in that sort of relationship. When it's adults-only, then I'm not as concerned, although I still worry that the adults, particularly the women of a man with x amount of wives, are coerced and brain-washed. However, when children are involved, then I become worried. If they are exposed to friends, peers, adults and livestyles outside of the polygamist family or group, and are able to learn enough to freely make choices about their own lives, fine. I simply worry that children raised in those environments are coerced and trained to become future polygamists, and are ignorant of other ways of living and different family structures. When the groups are closed and members policed, it's too cult-like for me, and I think the children should be removed. Furthermore, because of recent news, I do feel those environments create a breeding group for child sexual abuse.
There needs to be compromise struck which allows people to make the decisions they want in their relationships, but ensures the vulnerable are not being exploited, coerced or abused in any way. I'm not sure what that would entail, practically --- probably occasional visitations by social workers and child welfare, and opportunities to interact with those not involved in the lifestyle -- but I would be supportive of compromise.