Interesting topic. To be honest, I usually don't react much to Diana Krall music. I enjoy it, but I react like Schubert mentioned, like she's out of time with the band - and with me. To me, she's kind of a crooner, like Chantal Chamberlain, Norah Jones, Michael Buble. They sound to me like professionally produced singers singing other people's songs. Good background music but some sense of authenticity is missing. Kind of like the difference between a recital and a confession. I'm sure she has her moments, like the one you describe, but I don't follow her closely enough to catch those. I never thought of Dylan as a passionate singer, I thought of him more as a passionate poet singing. Kris Kristofferson also, but then I heard Kris Kristofferson sing the Ballad of Ira Hayes on a tribute to Johnny Cash and even though it was television, I felt way different than when Johnny Cash sang it. I felt the lament, the frustration and the pity of it all. There is scorn and condemnation when Kris sings it.
To me, there are singers/bands that elicit a powerful intellectual response, but not so much a powerful emotional response. Passion, to me, is in the latter category. The words and the music can be simple, even stupid, but the emotional response powerful. A lot of rock is like that. Pretty dumb lyrics, but very strong emotional pull - whatever the emotion.
Which leads me to think that artists are simply human. I'd imagine that some nights they are just going through the motions and other nights they are riding a wave of some sort and magic happens. Maybe how the crowd reacts charges them and the two feed off each other. Maybe each artist connects with different people.
I'm not sure if the artists that come to my mind as passionate are truly passionate or if they just sing/sung with abandon, or both, and I reacted in kind, but the ones that stand out in my memory are Sarah McLachlin, Etta James, Janis Joplin, Bruce Springsteen (when he was young), John Denver, Grace Slick, Emmylou Harris, Alison Krauss, Elvis, John Lennon, Paul McCartney and I know this may sound weird coming from the rock realm, but Klaus Meine of the Scorpions, Mick Jagger, Steve Tyler, Eddie Vedder and Jon Bon Jovi all struck me as passionate within their genre. Maybe Louis Prima and Louis Armstrong is in that category too. Absolutely infectious performances that just don't come from people who aren't passionate about they do and that are truly having fun. An honorable mention would be Jerry Garcia, who I typically found somnolent, but when he was singing Ripple? Mercy. Ditto Whitney Houston's cover of I Will Always Love You. She tapped into something there.
Wow, how easily so many come to mind and many more will come to mind as the day goes on, so I guess I believe that most of them are passionate, and like most humans, sometimes they are going through the motions because they are tired, or bored or distracted by other things going on in their lives and other times, the planets line up and they are absolutely on fire.