More fundamental question, is polygamy immoral?
Some non religious people can have multiple partners and go through God knows how many partners before settling down with just one. Some continue with the life style of debauchery. Which is immoral? A legal contract of 4 marriages or unlimited partners to mess around with no legal and emotional protection?
The funniest thing is when people in The West criticise polygamy in Islam yet in their own society it is very normal to have many multiple partners. Equal rights is the excuse people give but it can't be that its something else.