Just like Mark said in the Mark Lawson interview, guys like Glenn Worf are professional musicians, and that's their instruments. To me personally, a professional musician is indistinguishable from a magician. What they are able to achieve with their instruments is beyond any comprehension... I still remember playing with a professional jazz guitar player, I just gave him random chord progressions I liked and he composed brilliant solos around them on the fly, as if he knew those all his life.
John Illsley, on the other hand, is just like MK. Brilliant in his own right, and a solid player, but not exactly the most versatile. You can't put Mark in a jazz band. I think Glenn's bass lines are simple, but sometimes he really can't help but show his jazzy chops. Can't blame him