Having up to 4 wives is a privilege in Islam that given only to Muslim male. But unfortunately, this is the privilege that most common misused by males who follow their lust. Majority of Muslims who commit polygamy actually are not worthy for married in polygamy marriage. Even I have found at least two cases which non-Muslims pretend as Muslims only to do polygamy.
Mostly of polygamy marriage were not planned before, but happened after married men meet women who attract them. And they see privilege to polygamy as the chance to follow their lust.
Like I have written in another thread, there is a bad habit among Muslim males in Indonesia. They always miss salah, never fast in ramadhan, don't know anything about Islamic knowledge, but when their wives found they have been married other women, suddenly they turn into temporary scholars, gave 'lecture' about polygamy in Islam. This is the example when Islam is misused to legitimate lusty behavior.
I have read and heard many complains about polygamy. Many of those women complains, their husbands start to forget them after they married new wives. And I often read or heard cases which those wives hate each other because they think their love their 'enemies' more than them.
Mostly of wives who married in polygamy hate their husband other wives. And in mostly of polygamy marriage which I have found, husbands love one wife more than their other wives.
But it doesn't means there is no good polygamy marriage. I have found several good polygamy marriage which the wives and the husband feel happiness, and a wife and other wives are respect each other. I know personally with a man who married 4 wives in polygamy like this.
There are two things that make those polygamy becomes good polygamy.
First. The husband and the wives are religious Muslims. Even the husbands are ulama or at least have qualification to teach Islam.
Second. The second, third or fourth marriage are planned marriage. They had intention to have other wives, and then they start looking for other wives. Even in some cases, those new women proposed by old wives. Different than in bad polygamy which the husbands have intention to marry after they meet women who attract them.
Polygamy is privilege for Muslim males, but Muslims are not allowed to use this privilege only to legitimate lusty behavior. And is ulama duty to remind ummah not to misuse this privilege.