The verse in Sura al-Nisa mentioning the four marriages, mentions the orphans initially. These verses were revealed after the battle of Uhud concerning the widows and orphans of the martyrs. Does this in itself not precondition the permission of polygamy to the widows and orphans?
The verses in question donor give a command. Polygamy has always existed since the advent of civilisation. The idea that Qur'an introduced polygamy is wrong. In reality, Qur'an did not forbid it.
These verses were actually suggesting the solution to an acute crisis. A lot of widows were recently married and had young children. The Qur'an merely suggested the prevalent custom of polygamy to provide social stability for those in question. It also applied certain limits to polygamy. The first one limits the number to four. And the second cites equality amongst all of the wives. Those who would be unable to exercise equality were advised to refrain from polygamy, even if they intended to help the widows and orphans. Justice was a more desirable attitude.
Therefore the Qur'an actually set certain boundaries on the institution of polygamy.
This question was answered by Mr Ghamidi in Deen-o-Danish, an online TV session hosted by Dr Muneer Ahmad aired on Dunay TV. The text has been rendered into English by Mr Dhu al-Nurain.