No Country for Old Novels

Well, it seems the fad these days are to make novels into movies. I am Legend, No Country for Old Men, Golden Compass, and Narnia. Plus the dozen graphic novel adaptations such as Sin City, Batman, Spiderman, or Daredevil. Granted, these movies are artistically done, but my gripe is all about originality. Purely unique movies seem to be dwindling. Sure I can think off the top of my head of bunch of great original movies, but most aren't. This brings up the question: is Originality too big a risk for movies? Novels tend to be the 'proving grounds' for movies. If it sells or sold well, then they turn to the big screen. Is it too expensive and risky to go straight for the movies? Going to written form isn't that bad- but changing a book's format into a 2-hour movie can leave something undesired.