Why was the book 'speak' banned?

The book "Speak" by Laurie Halse Anderson was condidered both a challanged and banned book because of the use of language such as: b, a* hole, and b and also because of sexual assaultmeaning rape...i am currently graduating junior high school and enjoyed reading this book, i do not think that it should be banned because i believe that kids 13 and older understand that concept and know that it really isn't something to joke around with.