Simple answer: If it's part of the approved curriculum and the teacher assigned it then the answer is yes. They'll always be a reason to object to any book. The last thing we need are parents enabling their children to avoid their assignments. If we are to hold a class discussion on a novel then the class is expected to read it.
That being said I'm not a fan of the Harry Potter series I'd rather assign
The Arabian Nights by Andrew Lang Which I'm sure would get me into more trouble than Harry Potter.