I too take some exception to Metheny's bashing of Kenny G.
Not to start bashing Pat, but I have always found his style of jazz (much akin to Larry Coryell's playing) wholly boring, self indulgent and, saying absolutely nothing. It is like listening to a technician spout every nuance of arpegiated and scaled derivative, all fundamentally lacking in one main area -- communication.
Music should "speak" to us. Not be an exercise in our aural stamina of being able to listen to a piece in it's entirety, without the temptation to hit the STOP button.
Definitive jazz guitarists who truly speak when they play (IMHO) are people like Joe Pass, Herb Ellis, Barney Kessel, Wes Montgomery, George Benson, Lee Ritenour, and others.
Perhaps a more time spent listening to some of the above and even emulating their styles, would serve Pat and Larry better, but at this point they're probably too old and set in their ways to ever change and be open to new possibilities of creative interpretation.