Because they either A) want to jump on the bandwagon, or B) have low standards as to what constitutes 'good literature'.
I do think the over-the-top advertising has contributed to a record-breaking weekend. But the question I would pose is: "Is that really a good thing?"
Now tell me there's a direct correlation between "gross ticket sales" and "quality of movie".
Is it a good thing? Depends on what you thought of the movie. I love the books, and I like the series of movies they're working on, so to me, it's a VERY good thing. Like, who cares? Lucas was a little dumb to say that, IMO. Despite what anyone says, how much money a film makes has a major effect on what other films we see in the future, so it's worth paying attention to and caring about. If Potter makes money, they'll make more of them. Seeing as how I want more of them, I'm glad it's making a lot of money.
It's the same logic that has people like myself, Sades, and Spud, rejoicing at "Glitter"'s dismal gross.