I just wish that people would refrain from invoking moral principles when they aren't willing to follow them to their logical conclusion.
Yeah, that's really my problem with the "pro" side in this thread. Even if I happen to more or less agree with them, I really can't stand the sort of arguments they use.
Well, I think the point Mopsus raises actually crystallizes the key differences between polygamy and polyamory.
"Regulation" would seem to more affect the practitioners of polygamy than polyamory, and that may well be justified when we are talking about the legal institution of marriage. But when we're talking about polyamory and private relationships between consenting people, the need for "regulation" seems weak.
I hope this isn't an insulting comparison, but it's kind of like the difference between the state applying regulations to a registered business and the state applying regulations to a garage sale. There's not really any reason to intervene in the garage sale unless stolen goods or toxins are being distributed. There's not really any reason to intervene in a polyamorous, non-marriage arrangement unless someone is being harmed.