Hi Alec,
Let me begin by stating my thoughts are in response to your beginning thread only.

I find there are so many sub genres within Jazz. https://itunes.apple.com/us/itunes-u/jazz-insights-media/id405935692
This site has a lot of insightful knowledge about the genre and its origins. This is for those who wish to get a good overview of Jazz in short, easily explained lessons and examples.

I agree with your point on the solo. It should be the interpretation of the soloist as they navigate the chordal sequence. It is the job of the soloist to look outside the box of what has already been established by the melodist.

To your last point on CD sales, we have to consider the internet has expanded the exposure to music as well as artists not normally found in a typical record store. I would not put much stock on retail sales, including downloads, to determine the pulse of interest. I believe the jazz artists never did give it much consideration either as their goals were much different than to score a top 10 hit.

However unlike the popular music genres classical, blues, & jazz have a far more loyal following. The disposable nature of pop music and its fans blow through artists faster than a tornado. Hence the reason for the larger record sales. I think of it this way. Who will be buying Justin Bieber music 10 years from now? Who can tell me the million record seller of ten years ago and what music they are making today? Yet, people are still downloading music from artists of these more obscure genres you mentioned that have been dead for decades! So, it is a matter of perspective.

Cheers!