In this essay I have some contra arguments against polygamy.
Times when women were destined to choose between marriage and dying of hunger have passed away. Now women have more opportunities to study, work, earn money and be independent. 
First, women living in polygynous unions tend to marry very young (Early marriage could have negative health and mental consequences for young adults). Although the husband ought to treat them equally, most probably he would favour the youngest so it could cause arguments within the family. Second, who would control the age limit for a spouse? I guess that would be more complicated to control. If group marriage were to become normalized and spread, for society affects could be significantly negative. Historically, polygamy occurred in fundamentalist religious groups, as happened in the past; and these plural marriages (if happen) would be as coercive and destabilizing as they were those days ending in lies, jealousy, competition, conflicts.
According to statistics, more women in Russia are violated than, let’s say, in Saudi Arabia. Meanwhile, the sentences for rape cases are extremely unbalanced in Saudi Arabia. One woman had been gang-raped, became pregnant, and tried (unsuccessflully) to abort She was sentenced for 1 year in prison and 200 lashes. Is that really her fault for being raped?
As for me, the secret to a long happy marriage is equation between 2 partners (financial and emotional),not slavery or dependency in anyway.