Big budget productions have big budget scores. Big budget games have mediocre scores. This shouldn't come to a surprise to anybody in the industry. In almost every game the sound is almost always tacked on at the end. Composers are generally not paid what they are worth and as a result the music is not as good as it could be. In contrast the film industry pays it composers well and the music is a much bigger part of the production. Imagine Inception without it sound track. Imagine that the soundtrack was just an afterthought. It wouldn't be as good as a movie.
I honestly think that some developers thing that if music is simply just playing it is good. They don't care about fidelity at all
Personally, music is the one place where the least amount of money and time is spent in development. It really shows.