I've silently been following this topic with quite some interest.
First, let me say I'm not much of a musician. I've got some talent when it comes to writing memorable melodies, and I can pull off a decent sounding pop/rock-tune. When it comes to the art of orchestration, I'm quite lost though. I really repsect the skills of those more knowledgeable than me, which would be everyone in this forum, I'm quite sure.
Anyway, much of the discussion, at least from my perspective, seems to boil down to the question of what constitutes "real" music and the qualitites of a "real" composer. Most of the threads participants seems to have a very intellectual angle on the art of music, and that's all fine by me. After all, composing is in large part an intellectual excersise, requiring extensive knowledge. However, it's possible to convey emotions effectively without the same amount of knowledge as John Williams, and sometimes, the most simple piece of music can achieve this.
I'd like to mention John Murphy's Adagio in D-minor from Sunshine as an, IMHO, brilliant example of this. I guess many of you will think I'm musically retarded, but I absolutely love this piece of music. Even with my very limited knowledge, I could very well have written it, from an intellectual standpoint at least. There's nothing extraordinary going on, it's a basic chord progression consisting of 4 chords repeated over and over again, with a bass line as boring as Pachabels Canon in D. Yet, I can listen to it over and over again, and find it extremely beautiful.
I guess my point is that while you can approach music from a more scientific standpoint, at the end of the day, some aspects of music will not lend itself well to being measured, and these aspects sometimes might be the difference between a successful composer and an unemployed one.