And why in the world would any man want more than one woman!? That is the question I have always had for polygamists! 
I must admit I am equally confused about why any one man wouldn't want more than one woman. Polygamy/polyamory seems very natural to me. Also it's very practical when running a household. Also polyamory is wrong. You shouldn't mix Greek and Latin like that. It should be multiamory or polyphilia