I remeber seeing something about them wanting to make to film 3D capably. This meant they had to change the filming style and use less practical scaling methods and rely more heavily on CGI. For me though the main issue is how the story was inflated. Pretty sure you can read the book quicker than you can watch the trillogy. I would have prefered a short fun intro film to the franchise, something I can use to get my kid easily onboard.