I only read as far as the author's first email to a movie muckity-muck, but if he actually used that tone in his communications with the studio, it is very unsurprising that they mostly ignored and sidelined him.
The movies were, apparently, terrible. I didn't see them myself, but I am sure they're about as good as the other awfully YA-fantasy adaptations from that era that aren't Harry Potter (Eragon, which I'm pretty sure is what the XXXXs refer to and Golden Compass, for example), but this email is not the way that you exert influence over a major creative endeavor.
Edit: I went back and read the longer email. The actual discussion of improvements is potentially good, but the overall tone is one of arrogance and an assumption of superior vision, which is just not the way you make progress.
The movies were, apparently, terrible. I didn't see them myself, but I am sure they're about as good as the other awfully YA-fantasy adaptations from that era that aren't Harry Potter (Eragon, which I'm pretty sure is what the XXXXs refer to and Golden Compass, for example), but this email is not the way that you exert influence over a major creative endeavor.
Edit: I went back and read the longer email. The actual discussion of improvements is potentially good, but the overall tone is one of arrogance and an assumption of superior vision, which is just not the way you make progress.