"Often, when people were conquered or enslaved, their hair was cut as a recognized sign of slavery. It was also understood that this would serve as punishment and decrease the power of those enslaved.
The bones in the forehead are porous and function to transmit light to the pineal gland, which affects brain activity, as well as thyroid and sexual hormones. Cutting bangs which cover the forehead impedes this process. When Genghis Khan conquered China, he considered the Chinese to be a very wise, intelligent people who would not allow themselves to be subjugated. He therefore required all women in the country to cut their hair and wear bangs, because he knew this would serve to keep them timid and more easily controlled.
As whole tribes or societies were conquered, cut hair became so prevalent that the importance of hair was lost after a few generations, and hairstyles and fashion grew to be the focus."
Then you can understand why the LDS church and BYU care so much about the haircuts of the people.