jmc:
The source material isn't scripture but it shouldn't be ignored totally. It's the blue print of the franchise itself.
It's important for the film makers to understand as much of the the franchise they're adapting as possible, respect it and use what works while keeping the spirit, making it recognizable and creating a good adaption.
If something won't translate into a film there should be a pretty damn good reason for it and the changes have to make sense and be better for the franchise overall.
Yes, it's important to research the character and as many stories as possible to give the film makers the best possible chance of doing the character justice, but you still only need the basic foundations of the character to make it work on film. One could argue that Batman & Robin or Fantastic Four were close to the source material, yet they are awful movies. It's only one part of a successful movie, fans give too much credit to the source material as the reason of a film success, most of it is just damn good film making.