I had no idea that Metheny screed was still making the rounds. And I've never seen Kenny G live nor owned any of his albums, but I've heard some of his work over the years. And having been a pro 'bone player, I have some sense of how his thing stacks up against the traditional standards for jazz saxophony.
So, for the record:
Never heard him playing out of tune.
His basic sound seems full and vibrant, but that is increasingly hard to judge based on recordings that may have been altered -- for better OR for worse -- by some producer with a digital paintbrush.
He has good air control - I also understand he can circular-breathe, which is not easy, although those who can do it often use it as a parlour trick at the end of some song in a manner that is artistically questionable, like some number of singers you've seen over the years who court applause with the long note. But hey, I guess it's like the story about why dogs lick their private parts.
He's clearly spent time absorbing the jazz repertoire and the pop-funk thing as well.
And he's found a way to make a pile of change playing instrumental music on an instrument that is not a guitar/keyboard/drum. Way more change than most others that have explored the smooth jazz area, and way more still than those who have dedicated themselves to "Jazz." Let's never underestimate the extent to which jealousy of commercial success can fuel the dissing of someone's musicianship.
So let's get past the cheap criticism concerning his chops or musicianship.
However, what we may have here is the example of someone making some regrettable artistic/esthetic choices, and being boxed in by those choices.
Everytime I hear him, I hear excellent execution of material that has zero soul.
Yes, he can shade his tone, vary his attack and vibrato, and do things that seem colorful.
But I NEVER hear anything that feels "true" in the sense of spontaneous inspiration or probing to challenge himself or his audience. I feel like I'm getting music by the numbers; skillful, stylish execution tracking a tight formula that will not admit of deviation. To stick with the formula he has to perform at a pretty high level, but he has no freedom to vary from the formula, and boredom therefore quickly sets in.
Perhaps that's what you have to do to please the smooth jazz crowd, as my sense of that scene is that folks appreciate a little sophistication but don't want to be challenged but so much, and certainly don't want to hear sounds dissonant with the quaffing of white wine, dressing very well and plugging into a certain sort of lifestyle/image. So you get tasteful funky riffs, nicely executed while nobody breaks a real sweat, but you NEVER get the real funk that comes from people deeply working a groove, or the spark of excitement that results when players take that groove to a whole other level.
I'd think that if you live smooth jazz as a player, and you live there exclusively, you have to start wondering about your relationship to music and the cosmos. If you think music is a vehicle for ongoing exploration of your feelings, and for trying to express and share those feelings with others, then you can't or won't let yourself get stuck in that smooth jazz rut, because it seems that the smooth thing is largely about presenting music that is the sonic equivalent of a whole lot of yuppies at a networking party - everyone wants to look good, to make a good impression and to make a lot of connections, but ain't nothing interesting gonna happen while everyone is in that mode.
My question - when Kenny G is alone at night in his Malibu crib, does he take the horn out, and if so, what does he play?
If he uses the time to howl at the moon and express himself in a deeper and more profound way (for calibration, let's talk Wayne Shorter, who can imply a lifetime of rich experience with just a few notes on Soprano), then it's sad that we don't hear what the G-man has to offer to the world in that way, but at least he's doing it.
If he takes the horn out, only to reprise/refine his commercial riffs, that's even sadder still. 'Cuz that would suggest that the entire emotional life of Kenny G goes no deeper than the smooth jazz formula.
My gut tells me there is more to the man than the formula will reveal, but apparently we'll never know it from his recorded work.
Pretty sad, when you think about it.
But then, he needs your or my validation like a hole in the head.
Nothing wrong with that. 
