We live in a time where virtually everything is available to everyone (anytime) at the touch of a fingertip. Because the computer age has revolutionized the speed at which we both process information and produce information, there are a significantly greater number of choices available to the "entertainment consumer". Along with this glut of possibilities, a new way of listening to music has evolved.
In the ages-old tradition of putting the cart before the horse, recording technology is now influencing how music is made. Because digital technology allows us an endless amount of "tinkering" and "tweaking" (sounds like an old vaudeville team!), the most casual listener is now used to hearing recorded music where every instrument is isolated, separated in the mix and, in many cases, "layered" one at a time. Any vocals are now subjected to "Pro-Tools", an insidious device that allows the most discordant, arhythmic singer to sound like the most in-tune, in-time, almost life-like vocalist you've ever (never?) heard! (I know of at least two instances where the producers used this without the singers' input or knowledge!)
The problem, then, is that everyone across the jazz-pop-classical spectrum, is now used to hearing music that sounds like it was put together by a commitee of Swiss surgeons; there is no sense of a band playing together (even if they did play together, it's recorded and mixed as if they all played separately), no sense of danger, no bloody mistakes, for God's sake!
If a producer in today's world listened to Louis Armstrong crack a note, or Billie Holiday bend one, they'd be scurrying around like beetles (unfortunately not like "Beatles") "fixing" everything! It's bad enough in pop music, where every record is made by a "team" (in many cases, a team where the individual members will only meet each other in "virtual reality"); the beauty of jazz music is at least partly about that feeling of dancing solo on a high-wire, of chance encounters between beauty and ugliness, about emotions, "groove" and countless other human feelings.