That's because it really isn't the same church anymore. Like, at all. The mormonism of today, and the things they are taught is very, very different from the mormonism 100 or even 50 years ago. The [FLDS church](https://en.wikipedia.org/wiki/Fundament alist_Church_of_Jesus_Christ_of_Latter-Day_Saints) (the Warren Jeffs one) is much closer to the mormonism practiced under Joseph Smith and Brigham Young.

The considerably more famous branch of mormonism based out of Salt Lake City has changed a lot. As things like Polygamy, Blood Atonement, Adam-God Doctrine, the bans on black people from temples and the priesthood, the removal of the blood oath from temple ceremonies, and other smaller things the mormon church became much more, for lack of a better term, mainstream.

In fact, the vast majority of active members are completely unaware of the things that I just mentioned, or only know of a few of them. There are a few things that are the same, like the Book of Mormon, Pearl of Great Price/Book of Abraham, Doctrine and Covenants, and some ceremonies. But for the most part mormonism has changed so much that the average mormon sees themselves as just another christian, just with the "best" version of christianity. And they behave like it.

The FLDS church and the other smaller mormon polygamist secs that are much more loyal to what was taught by Joseph Smith and Brigham Young, are considerably less patriotic, for obvious reasons.

TL:DR Mormonism has altered it's doctrine and history so much that the average modern mormon has no knowledge (or at least very little) of the things that made the relationship between the US and Polygamist Mormons so contentious. Mormon Cults that have not bleached their own history are considerably less patriotic than the more well known version.

If you want to know more about mormon history and how it's changed over the years I recommend you read Rough Stone Rolling by Richard Bushman, No Man Knows My History by Fawn McKay Brodie. There are dozens of books and essays on the subject, and it's easy to get a little lost, so I recommend you start with those. If you need any help feel free to PM me.

I love talking about mormon history, and have studied it for a very long time, if you have any other questions I would love to answer them. It's not a topic I get to talk about very often. =)

This is a really interesting question! Actually, the church started off as being rather patriotic. The Book of Mormon has a passage in it that praises the American revolution and mentions this land as being a promised land. Things turned sour after the 1838 Mormon war in Missouri when the governor signed an extermination order against the Mormons. The Anti-Mormons in Missouri didn't like how the Mormon settlers banded together and voted in a bloc. Also, Mormons at that time tended to be anti-slavery and Missouri was a slave state. Joseph Smith went to D.C. to ask President Van Buren to help stop the persecution and protect the property rights of the 20,000 Mormon settlers. Van Buren refused to help for political reasons.

It was after this experience that Joseph Smith gave his "White Horse Prophesy" where he said that the constitution of the United States would be almost destroyed. During the presidential election of 1944, Smith didn't feel like he could support any of the candidates so he decided to run for president himself.

After Smith's death, with the Mormon church settled in Utah, there were further conflicts with the United States government. In 1856, a key part of the Republican Party platform was to abolish "the twin relics of barbarism: slavery and polygamy". The reference to polygamy is directed at the Mormons but Utah was also a slave state. President Buchanan sent the army to take control of Utah in 1857, which caused further antagonism between the church and the government.

In the effort to abolish polygamy, the leader of the church had to go into hiding and thousands of mormons were arrested. In 1887 congress passed the Edmunds-Tucker act that disincorporated the church and took all its assets including the perpetual immigration fund that was used to finance the arrival of new immigrants to Utah. Eventually, the church leaders were forced to abandon polygamy. This opened up the possibility that the Utah territory could be recognized as a state and that they could regain some political control.

It wasn't until Heber Grant became church president that a serious effort was made to fully heal the relationship with the government. The oath of vengeance against the United States was removed from the temple ceremony and references to vengeance were removed from church teaching manuals.

The period of peak patriotism was probably when David McKay was church president. He was friendly with President Eisenhower who asked one of the church apostles, Ezra Benson, to be the United States Secretary of Agriculture. Benson was occasionally overtly political in his addresses at the church semi-annual conferences speaking about issues such as communism and civil rights. Benson's views were closely linked with those of the John Birch Society.

TL;DR: The church was patriotic and then antagonistic and then over several decades became patriotic again once people forgot about polygamy.