I disagree. It's like a painter putting their name/face in a painting. I always smile when I hear his humming come through and I rather enjoy his own vocal counterpoint.
Don't ever listen to Keith Jarrett or your head will explode.
Incidentally, I was listening to the Köln concert as I read this. I laughed out loud.
Or a huge number of jazz musicians in general. In the jazz courses I took in college is was part of the training.
Really? What professional pianist besides Jarrett has audible vocalizations on their recordings?
Here's a segment of Billy Taylor where you can here him (and almost every time you can see his lips you can see him scatting along) from an incredible series called The Subject is Jazz
I have an Oscar Peterson CD with audible vocalizations
Erroll Garner
Hiromi Uehara
McCoy Tyner
Disliking something well liked doesn't make you interesting.
You exaggerate but it sure is irritating. It goes to show how someone's fame will generate all manner of excuses for behavior that would get slapped out of a beginner--or novice--or any other professional.
And--just guessing--I doubt many composers would appreciate the new, improvised parts.