I'm not so sure it's lack of soul (course it could be...) as much as not being able to get in touch with it.
A friend of mine asked me to play a children's Easter service with her this spring, and I ended up improvising during it. Not anything jazzy, and it was solo, but I think that's the first time I've ever done it. Wouldn't have even thought it possible a few years ago...and I got a lot of compliments.
Classical training has for a long time been about reading notes and learning rhythms. VERY strictly. A good orchestral player has to be absolutely spot on.
Not that one is better than the other, but they are very, very different. While jazz players complain that classical players have no feeling in their playing (all too true too often), classical players complain that jazz players can't 'really' control their instrument (also often true if measured by the classical stick).
I would love to play jazz. But it would be as scary at first as starting that first convo with a spouse about a SSM. I'm really glad that one of my better students took a opportunity to play with her school's jazz band this year. They didn't really want a flutist...but she's learning a lot. I think for many classically trained players, it's a bit like walking a tightrope with no safety net. I know far too many classically trained pianists, for example, who could move you to tears playing Chopin, but won't (can't??) improvise an accompaniment to a simple children's song.
That's not to say that classical players don't have heart, and the best usually could (and do, if not in a jazz setting) improvise as well. But we train for hours to keep a steady beat, while jazz players play for hours off the beat, and with what to us sounds like a lazy sense of rhythm (I know, it's not).
I suspect she has a soul - it's in a different place.
