Re: Reasons for polygamy
Simple answer , he is not obliged to as per the permission given in Quran. Again it is a permission , a favor , not an order or obligation:
marry women of your choice, two or three or four; but if you fear that you shall not be able to deal justly with them, then only one.” (Quran 4:3)
But since Islam is a code of conduct and this code of conduct dictates that a polygamist consort with his wife before taking another wife into marriage.
Why I say so here is the proof:
Allah ordered the believers to “consort with women in kindness” (4:19)
And of His signs is this: He created for you helpmeets from yourselves that ye might find rest in them, and He ordained between you love and mercy. Lo! herein indeed are portents for folk who reflect. (21)
So the love and mercy between a husband and a wife can only be real love and mercy if a husband consorts with his present his present wife before he marries another one.