Demonstrated a broad understanding of the issues
The thesis statement:
... The global success of Harry Potter books is due to the special book-launch, the film of the book, and widespread marketing of Harry Potter merchandise.
proposes that book launches, the film, and merchandising played the most important role in the book's success. The underlying theme of the statement indicates the essay will argue that commercialism is much more effective than other forms of publicity. As a discussion question, you will need to consider these other forms and acknowledge their influence on book sales. The number of these other factors will depend on the extent of your brainstorming and research, but could include:
... positive discussion of the book in the media and word-of-mouth promotion by readers
Therefore, you will need to incorporate a sentence that introduces these alternative viewpoints, for example:
... It is possible that positive discussion of the book in the media, and word-of-mouth promotion by readers, could also have influenced book sales.