I grew up mormon in North Carolina. There is so much that is great about belonging to a community and learning to prioritize and live values, especially when those values are very unique to you.
There is also a lot of harmful teaching and practice in the mormon church and culture. One strand of which is the victim mentality and inability to update narratives and stories. Try telling a mormon that Joseph Smith really was caught sleeping with his maid, it wont go over well.
I think Mormonism is dying in the US because there isn't a place for diversity. Not just for race and LGBT folks, but a diversity of thought. That drives young people out of the mormon culture. So it's not surprising that the less 'mormon' the youngest generation becomes the less likely they are to vote like mormons.