The academy award is called "best adapted screenplay" and awards the best screenplay (by oscar standards) which happen to be an adaptation. Whether the adaption if faithful or improves of the source material is not a factor, only the resulting screenplay.
I'm not disputing the movie is cliched oscar-bait. That is the kind of movies the oscars awards.
Exactly. Things like sequels as also classified as adapted. Borat got a nomination for best adapted screenplay because it was based on the character from the tv-show. But the screenplay is supposed to be judged on its own merit, the academy members is not required to have read the book or whatever.
I'm not disputing the movie is cliched oscar-bait. That is the kind of movies the oscars awards.