The context in which the Surah allowing polygamy was revealed was following the Battle of Uhud in which many female orphans were made following the deaths of their fathers. Back then, orphaned girls were abused by society and had their inheritance stolen - marrying more than one wife protected those girls and helped the population grow following a battle in which many men died.
Having said that, polygamy can be dangerous for a man - it's permissibility in Surah Nisa is on the condition that the husband treats all of his wives equally and justly. The same Surah then goes on to say that man is not capable of being completely just. Many men today marry several wives, but have obvious favourites, which is against both the Quran and the Sunnah of the Prophet salallahu alayhi wasalam