It's unclear exactly why Kenny G is the object of so much vilification, particularly from jazz musicians. Kenny would probably never claim that what he plays is jazz.
- Is it because he's a mediocre player? There are plenty of mediocre players around. I can can go to a local club any night of the week and listen to far worse players.
- Is it jealousy because he's successful? Unfortunately talent and commercial success have a very poor correlation. Just listen to half the Top-20 hits from the last fifty years.
- Is it because he's pretentious? A lot of successful people are: just look at some of the politicians and company mangers around.
I get the impression this is like the weaker kid in a school class who gets picked on by a couple of pupils, and then everyone jumps on him. There seems to be no objective justification for the hate, even if one assumes it's possible to be objective at all about music beyond the most basic level (e.g. wrong notes)
There's an interview with Pat Metheny where Pat covers some of this. He would have been prepared to ignore Kenny G, but what really sends him off the rails is Kenny G overdubbing himself on top of Louis Armstrong's "What a Wonderful World". This is a simple pop ballad, and probably the least musically interesting thing that Armstrong ever recorded, but the interview turns into a rant:
But when Kenny G decided that it was appropriate for him to defile the music of the man who is probably the greatest jazz musician that has ever lived by spewing his lame-ass, jive, pseudo bluesy, out-of-tune, noodling, wimped out, fucked up playing all over one of the great Louis's tracks (even one of his lesser ones), he did something that I would not have imagined possible. He, in one move, through his unbelievably pretentious and calloused musical decision to embark on this most cynical of musical paths, shit all over the graves of all the musicians past and present who have risked their lives by going out there on the road for years and years developing their own music inspired by the standards of grace that Louis Armstrong brought to every single note he played over an amazing lifetime as a musician.
The whole article is worth reading, but there is nothing objective about Pat's opinion.
The question is garnished with a photo of Miles Davis sitting next to Kenny G and looking somewhat less than happy. The claim that this is evidence of Miles' dislike of Kenny G doesn't hold up. I don't think I've ever seen a photo of Miles smiling except on the cover of his 1966 album titled, with a touch of self-irony, "Miles Smiles".