Taking a book off of a mandatory reading list is not a question of censorship, but of sponsorship. If a book is offensive to parents, that is reason enough that it should not be made mandatory.
The parents are morally responsible for their children's education: they have a right as well as a duty to determine the content of the educational program. Moreover, the parents are paying for the education; they ought to control the product they are buying.
"To compel a man to furnish funds for the propagation of ideas he disbelieves and abhors is sinful and tyrannical."
Good point.
The books are no longer banned, and in some cases never really were. But the school system is promoting the books to kids as banned books in order to get them to read them.
Another good point. It's more the ALA and librarians who are promoting "Banned Books Week" to increase their own visibility, though. It's the one time a year that a lot of people actually hear anything about libraries.