By the way, doesn't it just STEAM you that Utah was forced to ban polygamy before they were allowed to join the Union. I mean to say...what an outrage! Too bad the gov't back then wasn't as "smart" as we are about what the Constitution really means.
From my reading of Utah history, Utahans chose to get rid of polygamy, so they could elect their own government, rather than have the US gov't send them leaders that they did not like. They also had to disband a religious party, called the Mormon People's Party, and move toward the Democrat-Republican two-party system to achieve statehood. A plurality of the Utahans chose the Republican Party, and when the Republicans started gaining strength in Congress, they were able to usher Utah in to the Union. It was more than just a struggle over a definition of marriage.
Besides, you should be glad they accomplished it at that point in time. What if Utah had retained territorial status well into the 20th Century, then had made an attempt at statehood in, say, the late 1960's/early 1970's? Would the society of the sexual revolution have allowed them to enter with polygamy having been an established religious principle for over a hundred years? My guess is that it could have been possible. You'd have a nation with two distinctly different notions of what marriage entailed. It wouldn't have been that hard to envision a third. We'd probably have legal gay marriage by this point in time, if things had gone different with Utah.
As for government being "smart" about how it treats marriage, it was the prohibition against selling contraceptives to even MARRIED couples that gave us the Griswold vs. Connecticut SCOTUS ruling in 1965. You might recall that in that decision, the SCOTUS first started playing around with the shadowy notion of "penumbras" "emanating" to create the privacy right that was not explicitly mentioned in the Constitution. If the Roman Catholic Church had not been so forceful in including married couples from obtaining the right to control their fertility, we might not have had this ruling, which spawned Roe vs. Wade a mere eight years later.
Expect the words from Griswold vs. Connecticut: "We deal with a right of privacy older than the Bill of Rights - older than our political parties, older than our school system. Marriage is a coming together for better or for worse, hopefully enduring, and intimate to the degree of being sacred. It is an association that promotes a way of life, not causes; a harmony in living, not political faiths; a bilateral loyalty, not commercial or social projects. Yet it is an association for as noble a purpose as any involved in our prior decisions," to find their way into a future decision involving gay marriage.