The questions brought forth by RedJamaX below, I thought, were very reasonable questions that need clarification for a better understanding of Islam. So this thread would be my humble attempt to clarify the questions RedJamaX raised.
To understand this highly misunderstood topic of polygamy in Islam, you not only have to understand the context and regulations regarding polygamy in Islam but also the system of marriage in Islam. It is certainly not an allowance of lustful sex for men as they please.
This is what the Qur'an says about it : "...Marry women of your choice, Two or three or four;
but if ye fear that ye shall not be able to deal justly (with them), then only one..." (Al-Qur'an 4:3)
First the context ...
"Karen Armstrong explains much the same in her book entitled Muhammad: A Western Attempt to Understand Islam. She says:
We have to see the ruling about polygamy in context. In seventh-century Arabia, when a man could have as many wives as he chose, to prescribe only four was a limitation, not a license to new oppression (Karen Armstrong, Muhammad: A Western Attempt to Understand Islam, Victor Gollancz Ltd., 1991, p.191)." [1]
"Polygyny provides a solution to some of life's problems. When there is a shortage of men, for example after a devastating war, many women will be unable to find husbands. Most women in that situation, given the option, would rather be a co-wife than no wife. If one maintains a strict monogamy in such a situation, moral depravity is bound to result. " [1] Furthermore, "Polygyny also sought to solve the problem of the existence of large numbers of widows and orphans who were left to fend for them." [2]
Now that we know the context, please note that Qur'an only permits a man to have four wives but does not command it. And in fact "less than 2% of Muslim marriages are polygamous" (A Muslim Primer, p.180). We shall see why ...
First of all, marriage in Islam puts a huge responsibility on the men. From the financial point of view
1) A man has to give a mutually agreed upon gift(mahr) to his wife for the marriage (just to show a perspective on things - currently that is roughly around $10,000 - $20,000 for middle class muslims in USA)
2) A man is solely responsible for providing for his family even if the wife works (so everything the wife earns is hers alone and everything the man earns is theirs)
So in the case of polygyny, in order to be just(equal) as the Qur'anic verse above states, the man has to provide(house, car, money etc.) equally to all his wives." Moreover, "A man must divide his time equally among his wives. He may, for example, spend one night with each wife on a rotating schedule.
If a man cannot maintain justice in the treatment of his wives, the Qur'an stipulates that he is to have no more than one wife." [1]
After knowing all this, I don't know how many men would willingly opt for polygyny except those who are really sincere and not in it for lustful physical relationship. So it is very clear how Islam has checks and balance in everything it stipulates. And everything the Creator stipulates is for a reason and for the good of humanity cause no one knows us better than Him. See what non-muslims say about this :
Why are there virtually no polyandrous societies?
Finally, I would point out that it is really hypocritical of the western society where polygamy(mutually agreed upon relationship with full responsibility) is 'illegal' and cheating(breaking covenant, without any responsibility and often involves lustful desire) with your spouse is not.
References:
[1]http://www.islamcan.com/common-questions-about-islam/why-does-quran-allow-muslim-men-to-have-four-wives.shtml
[2]http://www.islamiska.org/e/chap3.htm
And yet quite another interesting take on this matter :
The paradox of polygamy II: Why most women benefit from polygamy and most men benefit from monogamy | Psychology Today
It is not true that only Muslim men get beautiful companions in heaven.
Even though in a few Qur'anic verses, for example, 44:54, is commonly translated as "So; and We shall join them to fair women with beautiful, big, and lustrous eyes", "the Arabic word "hoor," is used (*,*,*,*) Now, the Arabic word "hoor" does NOT specifically mean: "females/maidens." The Arabic word "hoor" is actually the plural of ahwar (applicable to man) and of haura (applicable to woman) and signifies a person having eyes characterized by hauar a special quality bestowed upon a good soul, male or female in paradise and it denotes the intense whiteness of the white part of the spiritual eye. Therefore, the Arabic word "hoor" refers to both male and female, and the correct translation in these verses are: ""virgins, beautiful ones, beautiful mates, beautiful souls," which refers to MALES as well as females." [3]
And that makes sense when you read the verses before it : "
Lo! those who kept their duty will be in a place secured. Amid gardens and watersprings,Attired in silk and silk embroidery, facing one another. Even so (it will be). And
We shall wed them unto fair ones with wide, lovely eyes." (Al-Qur'an 44:51-54) . The underlined lines above could equally apply to male or female.
Bottom line is nothing unfair would be done to anyone.
Here is what the Qur'an says about that :
"Whoever does righteousness,
whether male or female, while he is a believer - We will surely cause him to live a good life, and We will surely give them their reward [in the Hereafter] according to the best of what they used to do." (Al-Qur'an 16:97)
"And give good tidings to
those who believe and do righteous deedsthat they will have gardens [in Paradise] beneath which rivers flow. Whenever they are provided with a provision of fruit therefrom, they will say, "This is what we were provided with before." And it is given to them in likeness. And they will have therein
purified spouses, and they will abide therein eternally." (Al-Qur'an 2:25)
Note that it doesn't say spouses for men only.
Further, according to one of the sayings of Prophet Muhammad(pbuh)
"Narrated Abu Huraira: the Prophet said, "Allah said, "I have prepared for
My righteous slaves (such excellent things) as no eye has ever seen, nor an ear has ever heard nor a human heart can ever think of.' "(Sahih Bukhari, Book 93, Number 589)
"
And the one who has brought the truth and [they who] believed in it - those are the righteous.They will have whatever they desire with their Lord. That is the reward of the doers of good" (Al-Qur'an 39:33-34)
This verse pretty much defines the limit of what any male and female can have in paradise,
that is no limit whatsoever - they can have whatever they desire.
Finally, According to Islam, God is the most Just and will do no injustice to anyone. One of the attributes of God is Al-Adl (The Just). "The One who judges between His Servants in this life and the Hereafter with His Justice and Fairness. He will not oppress anyone to the extent of an atoms weight and none will be made to carry the encumbrance of another. No servant will be recompensed in a way that is greater than the magnitude of his sin, he will be given only what he deserves. Not a single persons right will be denied, He is Just in His regulation and decree." [Taken from godnames.org/godnames.php?f=godnames_36_50#50]
"Then, on that Day,
not a soul will be wronged in the least, and ye shall but be repaid the meeds of your past Deeds. Verily the Companions of the Garden shall that Day have joy in all that they do;
They and their associates will be in groves of (cool) shade, reclining on Thrones (of dignity);" (Al-Qur'an 36:54-56)
This further confirms that both Male and Female will be dealt with full justice and no one will have any complaints. I think that is Fair.
Now let me finish this with a statement a muslim women wrote while discussing gender equality issues in Islam...
"On the other hand, only a woman can be a mother. And God has given special privilege to a mother. The Prophet (pbuh) taught us that heaven lies at the feet of mothers. But no matter what a man does he can never be a mother. So why is that not unfair?" [4]
The answer lies in - "But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah(God) Knows, while you know not." (Al-Qur'an 2:216)
[3]http://islamic-replies.ucoz.com/2/Only_Males_Or_Both.html
[4]http://www.suhaibwebb.com/ummah/women/a-woman%E2%80%99s-reflection-on-leading-prayer/
You dont have to believe the path you follow is perfect to follow it either 
