Then I met some semi-pro jazz musicians, who just did the opposite. They literally played everything and wanted to perform well in every context. They practiced hard to be able to substitute in classical orchestras, big bands, soul and funk bands, country, western and even Bavarian marching brass band music. They were open to everything and tried to learn and assimilate every style they contacted to take a piece with them into their own music. Of course any musician can have this openness and there is some opening happening in classical music. But in my experience I most often found this with people who played jazz. Maybe the improvisational training with chords, scales, and harmonic functions helps to quickly understand other musical ideas.
This musical openness of musicians beyond genre boarders is my (personal) idea of what jazz music and jazz musicianship could be about today.
This is a really GOOD point. I agree 100%, being a fairly accomplished jazzer DOES provide you with the tool belt to actually learn and play other genres pretty 'easily', for lack of a better word. So I would add that to my list of ...er....
"justifications"....
I have done this a number of times as a bandleader. We may have had a client or a club that wanted a special theme-night of a particular music or even decade, or such. It was actually very smooth to pull that off with a group of jazz players.
My group is about to do that now, in two days. Mardi Gras, Fat Tuesday, Carnivale ...in the borderlands desert !
I have had the fortune to attend a New Orleans Mardi gras and back in my college days, Zydeco music got really "hot" in pop circles and radio for around 3 or 4 years....and I always wanted to play a Zydeco show with some other down-home Louisiana style music in there.
A few bands here do Mardi Gras gigs - but in honestly all they do is throw in a few Trad Jazz tunes to their regular jazz repertoire, then revert to Great American Songbook or bop...but audiences here know no better. The bar is pretty low.
I was approached with doing a Mardi gig and decided I really wanted it to be a melange of New Orleans style music.
Nobody in my group here was familiar with a lot of the material...the Zydeco, New Orleans Funk (The Meters, Dr. John, The Neville Bros, etc), of course Dixieland, Delta Blues...we are even gonna do a NOLA Funeral Dirge.
As my trumpeter (young guy, grew up here) said when approached, after listening to the playlist: " I have never heard any of these bands, but this is doable, it isn't HARD to wrap our heads around, it's just something we are mostly unfamiliar with".
We had three practices but honestly, after one practice it came together so quickly that I was almost giddy.
But yeah, they are jazz players/singers, they prepared for the practices, so this was not by any means too big a piece to bite off.
Applies to other genres of course. I have been involved in Rock shows where, likewise, the jazz players occupying the parts just did a more thorough, precise job of learning and playing the material than a rock cover band would do.
Jazz does give you those tools.