Here's a different take on the Twilight phenomenon "Do Twilight Fans Get Flak Because They're (mostly) Girls?" The question is that if it was less of a romantic book, and more of an adventure book, similar to the Harry Potter series, then maybe the book wouldn't be so bedeviled by critics.
However, Harry Potter hasn't been as loved by critics as this blog seems to suggest.
Here's an article on all the book banning of Harry Potter. More details about the Potter censorship battles. Here's The New York Times' children's book editor, Laura Miller's take on how long a book takes to become a classic, and why Harry Potter is yet to be one. She also writes about the children's literature publishing world in that article for Salon. Christian bookstores and some Christians haven't been very enamored with the Potter series, either.
The list is endless, but Harry Potter is not particularly beloved among everyone and has taken his hits and arrows. Twilight is paying the price for popularity as well.