I don't have a huge investment in this debate; I am schooled in Jazz but am not a "professional" musician and my schooling is limited by those standards. I love Jazz, but recognize it only gets about a 3% market share, and this doesn't bother me. I don't think this is due to any deficiencies in the general public; it just is the way it is.
I am surprised that there is so much resistance to the idea that jazz is "more difficult" to play than more popular styles. I wonder how many in this camp actually study/listen to/play jazz. Jazz is not just swing, or playing "autumn leaves" out of a fake book. There is so much diversity in Jazz, it really seems that anything is possible, but the common theme is an emphasis on excellent craftmanship. To say that jazz lacks anything (heart, soul, attention to timbre, etc) means that the speaker has not listened very hard, imho.
I do believe that Jazz has a higher bar to entry than any other popular style. Sure, lots of players in other styles have studied harder/play better than an average jazz musician, and world class musicians of any genre require a lifetime of devotion. However, you can't just jump into jazz and be playing in a couple of months like you can with bluegrass, rock, reggae, etc. Jazz IS more difficult, and I think you would get the same opinion from drummers, guitar players, keyboard players, etc.
This idea seems to be upsetting to a number of people, and I don't know why. Does it upset people when they are told that playing classical music requires a deeper skill set than playing the blues? This shouldn't be controversial.
But...this does not mean that jazz is BETTER than any other style. Phish at their best hit levels of improvisation and technique that is on par with the best jazz combos. The Roots can lay down anything. Examples abound.
Perhaps it comes down to the Jazz police, as to why Jazz is not popular. As I mentioned before, when swing was popular in the mid 90s, it was dismissed as "not real swing." Jazz/electronica/DJ fusions and experimentation (St. Germaine, UFO, Acid Jazz) are not "real jazz." When Joan Osborne sang "Lover Man" on Greg Osby's Public album, people were quick to say "oh, she's not a jazz singer." Examples abound.
How can Jazz be popular when every popular expression of it is derided as "not real jazz?"
I think Jazz will last forever, and always have an influence on popular music. It just might not be taking the forms that everyone will accept.
Here is a song to enjoy this morning. i don't know if it is Jazz:
William Parker & Leena Conquest - Corn meal dance (2007) - YouTube