It won the box office this weekend. Even if the sequels weren’t already a foregone conclusion (the book series is a trilogy), that would be enough for a studio exec to green-light them.

And by the way, can we quit trying to discern the political messages in these movies and the books and enjoy them for what they are?

It’s not a “political” message, but this series does, in fact, have a theological agenda. The movie doesn’t make it as clear as the novels that Phillip Pullman is railing against the power-hunger of theocratic institutions in general; the Catholic Church in particular. You’re right in that Harry Potter is primarily just an entertaining yarn, but His Dark Materials (the proper name of the Compass trilogy) doesn’t just demand you discern the message, it wears the message on its sleeve.