Whatever proceeds hereon is based upon logic. I am not a Mufti or an Islamic Scholar. But without knowing the full details of the Quran and Sunnah, I would like to regardless venture onto this topic.
The birth of Islam happened through Prophet Muhammad (PBUH). Then other Sahabis started to convert to Islam. In other words, Islam was in its infancy.
Conventional wisdom was of multiple Gods (or Paganism). In this environment, Muslims were few and far between. In other words, there was friction between the two forces of Paganism and Monotheism.
This resulted in war. Men fight wars. So, the ratio of man to woman must have been biased towards women.
There are two conditions that are required to engage in multiple marriages: One is sexual potency (or ability), and the other is economic ability to support all wives. It is encouraged that every wife is treated equally. So, for this reason, that the ratio was probably off, multiple marriages were accepted. Islam is a secular religion. In other words Multiple marriages were beneficial for women: Both to get economic protection, and to get sexual gratification. How does this apply now?
World war 1 and 2 claimed millions of lives. Another war may happen between Muslims and their adversaries. The above– regarding multiple marriages– might apply any time in the present or the future.
Another reason Multiple marriages were probably allowed is procreation. That is, at that time, multiple marriages would increase the number of Muslims. In this way Islam would spread.
Any informed comments will be appreciated.
N.B Please bear in mind that we are dealing with very small numbers of Muslims engaged in wars: Say there are 300-odd Muslims engaged in a war, then the ratio between men and women becomes very lopsided even if 25 percent of the men die. Assuming there are 300 Muslims, 150 men– if 50 percent of men die, we are down to 75 men. Women become 2 times more than men. With caveats such as libido and economic ability, the sample of men who can engage in multiple marriages is even smaller.
We can also use reverse engineering here: If the ratios between men and women are equal, then (suppose) if one man marries three women, 2/3rds of the men cannot marry a woman (because there are no women to marry).
Additionally, reciting the Quran gives belief. In other words, mentally we are all here and there. However, reciting the Quran can automatically increase belief and diminish doubt.
Recitation of the Quran also happens during prayers. This is to give belief. Then when we bow down to God during Salat, it cuts our ego: We regard a deity that, to us, is much greater than us.