Joseph Smith knew full well what would happen if he restored the practice of celestial plural marriage. Why then did he do it? What did Joseph know that we don't? There must have been a very good reason to put his life on the line for the that principle.
As far as it being unfair to women, that all depends on your prospective. Is it fair to a woman to not ever have the option of marriage due to the shortage of honorable men in the church? Or to be forced to choose from the possibly not so shiny"available" men. Etc.
If you were a woman, would you rather have 10% of a godly man or 100% of an ungodly man? As you have noted in church history, many women, of there own volition, chose the godly man despite the sacrifice. That is not to say that there aren't honorable "available " men in the church, but from the statistics I have heard, the honorable women in the church out number the men, and the gap is ever widening. I am quite interested to see how that problem is solved.