Maia Lynay Rodriguez answered...

Many of the prophets of the old testament practiced plural marriage under Gods direction; among them Abraham, Issac, Jacob, David and Solomon. It is an ancient practice. I know that God only allows it's use under his authorization. There have been instances, one in the Book of Mormon to be exact (Jacob 2:27-30) where God has condemned the practice. Given the fact that God has, throughout history, alternately prescribed and condemned the practice I believe that it is a situational doctrine where God, having all of the information, and us not having it all, reserves the right to make a judgment call, taking all things into consideration, and either prescribes it or ends its use, basing his decision on the needs of the moment and all other factors involved. So the answer to this question is that the church practiced polygamy because God prescribed it at that time, and we don't anymore because God revealed that the practice was to be discontinued. When plural marriage was practiced only a handful of men were selected by God to participate. It was, by far, not practiced by all men or women in the church. The ones who participated were obeying a commandment from God, not necessarily seeking out the practice.