**** The notion / sense, that Jazz must 'progress' or 'Improve' or move on to something Mo' Better is the major problem. It is only in the Jazz genre that we have this situation. ****
Always hated the term "progressive" as used in political circles. I don't believe anyone has used it here re music; and certainly not the term "improve". Evolve, yes. But to conflate that with "improve" is very telling of the mindset of blind protectionism that wants to draw that circle around a certain period in the music. Btw, this is another one of the themes that is continually misrepresented here and needs to be corrected. As was pointed out, "déjà vu all over again"... and again, and again.
**** I could junk Mozart in favor of Philip Glass. After all, his music is 'Modern'. Yeah right ****
That's like saying "I could junk Bird in favor of Kenny G"; while ignoring all the great modern jazz artists because, just as during the "Golden Age", there are some knuckleheads out there producing crap. See, that's the real problem, too many broad strokes and not enough depth of thinking about all this. Of course, you are mistaken about how the notion applies to other genres. All music (all art) evolves and is widely recognized to do so. You don't like the notion and that is why you don't like a Classical music that has evolved beyond Mozart and Beethoven. It is ideas like "most current music lacks life" that are so ridiculous and need to be countered. It is not that the music lacks life and coherence; it is that some listeners are locked in a narrow sphere of awareness and are of a personality type that needs that idea as a security blanket. "Knowledge" that has notions like that as a backdrop is questionable at best.
Cheers.