In addition to The Lord of the Rings, look at Harry Potter and the number of movies that tried to duplicate its success thanks to its reception. While marketing campaigns no doubt play a part in a movie's success, pretending that previous entries don't make a difference is utter bull. If anything, their success acts as a marketing campaign itself, nevermind helps subsequent marketing campaigns that much more. After how much I liked the first seven Harry Potter movies, do you think Warner Bros. is really going to have to try hard to convince me to see The Deathly Hallows Part 2? I don't think so. The same can be said for The Dark Knight and The Dark Knight Rises. God knows Marvel is banking on the success of The Avengers, thanks to the reception of Iron Man, The Incredible Hulk, Thor, and Captain America. Getting people through the door is one thing, keeping them invested is another.