AA is making the argument that man hours expended contributes to or defines value. I personally see that as another guise of the commodification idea: an "hourly wage" for music composition. The more time you put in, the more compensation you should receive.
Unless we can agree on certain extra-musical presuppositions, there is nothing to say that a piece which took 12 years to compose is superior to one which took 12 seconds. It may be that we can indeed agree that the former deserves more praise and championing, but for no reason having to do with the music itself.
I don't actually think that we need to find some kind of enchanted over-arching rationalization for music in and of itself. For me, music is very much a social, psychological, economic and cultural phenomenon We can do very well looking for an understanding from these angles. We can also look at its bare bones to understand the raw material from which it is derived, an activity which certainly has its place, but at that point the grounding becomes softer and matters more unsettled.
This is why I'm not sure music fits so well into the academic world just by itself. You normally have to add other grounding before it makes much sense. There is sort of an exception in that inter-subjectivity arises (a la memes) so people start to agree things because everyone else agrees them...again though, that's sociological, psychological and historical.
AA, your own musical story seems to be largely sociological and psychological, much like everyone else's. Nothing to be ashamed of, it's just human nature. I also think you are expecting too much of music academia. If you want to stand up for your own interests, write music which is true to you, collaborate with it, get it heard, see what people think, have fun. The world outside academia is full of rich musical traditions/disciplines which are barely even acknowledged inside institutional walls. Don't fall into the trap of thinking that music has to be paid respect in an academic context for it to have some kind of value.