@chowkwan
"I stand back to no one in my admiration for Ella Fitzgerald's technique but all the vocal fireworks make for precious little emotion. Billie Holiday on the other hand makes you feel she's singing just for you."
You do realize that you're describing your subjective experience here as though it were objective, right?
The issue of whether or not an artist communicates emotion is complicated by the fact that the listener is an integral part of the experience. What the listener perceives is deeply conditioned by all sorts of subjective factors.
I've played CDs that I find very emotive for friends, only to witness them sitting impassively. Clearly they've had a very different response. I don't believe this disparity can be explained simply by analyzing how technically proficient the artist in question may or may not be.
I'm guessing there are many fans of guitar shredders who'll assert they experience intense emotion from listening to their idols' gymnastics. For me, it's about as gripping as watching someone lift weights but they'd probably find Otis Rush or Roy Buchanan boring.
One guy who started out as a shredder and evolved into (as I hear him) a highly emotive player is Ritchie Kotzen. His Live in Japan YouTube video is a great example.
Great topic, BTW.