[BluffTHIS!]

Because the life of Jesus and His redemption marked the beginning of a new covenant given to men to replace the old. Thus He also changed the previously more lenient rules regarding marriage which allowed Jews to divorce. And because God has a preferential option for the poor and the humble, and wishes us to as well. A reading of the Gospel shows that the poor and humble are the ones to whom Jesus often showed favor, and in fact condemned most of the rich and powerful. Part of the reason for this is that as I said in the thread I started on why some won't believe, those who are humble are more likely to be receptive to the Word of God and to act justly toward other men.