I'm not sure directors who try to transcend the source material by changing stuff have a worse track record than those who stay pedantically faithful. Some stories, frankly, need changing. Where would we be if Spielberg and Coppola had set out to stay intensely faithful to the novels of Jaws and The Godfather? Even Lord of the Rings would have landed with a thud if it had been as geekily faithful to the original. But of course, there are times when you can seriously botch it by changing something, usually something non-superficial. The sense of when to change something and when to remain faithful is pretty fundamental to being a good storyteller anyway, so the sense of what to change and the relative stupidity of the changes tend to go hand-in-hand.
What I'm saying is that it makes sense for a hacky director to remain pedantically faithful to the story, because they know they don't have enough story sense to know what needs to be changed. Of course, Fincher is not a hacky director, but at this point I feel like there's actual pressure from studios not to change anything for fear of fanboy wrath (which is my answer to Gabe T). Which is exactly why you need directors who are willing to push back against the system. Obviously, some people will beset off over any change, but if they're good, people get over it pretty fast.
I have no experience with the book or the movie of Dragon Tattoo, but it really sounds like it's another Jaws or Godfather in terms of the source material--pretty OK pulp that captured the zeitgeist and is begging for a real talent to elevate it into something special. But it also sounds like that's not going to happen this time out because it's not the 70s anymore.