Doctrine and Covenants 132:38 helps clear this up.
38 David also received many wives and concubines, and also Solomon and Moses my servants, as also many others of my servants, from the beginning of creation until this time; and in nothing did they sin save in those things which they received not of me.
The problem isn't polygamy, but the unauthorized practice of it. The main point through-out Jacob 2 is simply unchastity of all kinds... not just unauthorized polygamy. In our day this could refer to the husband who looks at porn and masturbates, who has extramarital affairs, or who gets rid of his wife to marry some one else. It can also refer to wives who are involved in the same wrongful practices, however for them it may take on a different form such as reading romance novels and fantasizing inappropriately or having more intimate relationships with facebook friends or other networks than they do with their spouse. The point is we are supposed to be faithful to our companions and at the time Jacob was speaking to these people the men needed to be called to repentance.
The Lord is just as concerned with broken hearts today as He was in Joseph Smith's day and Jacob's day.
Last edited by SpiritDragon; 03-14-2013 at 10:22 AM.