Because they spark controversey and when there is controversey not everyone is happy. Happiness is what the government want the people to have at all times. So they have peace in society.
The books were banned because they promoted individual thoughts. In the society they all lived in, it was easier to have everybody agree; therefore burning the books.
Fahrenheit 451 is banned in some areas because it contains offensive language and content. A parent complained to the superintendent of West Marion High School about the book's usage of the phrase...