i don’t buy your assumption at all regarding jazz singers. I don’t know about opera or violinist but I’m a huge fan of Early Jazz vocalists.
Billie Holiday - April In Paris
Ella Fitzgerald & Louis Armstrong - April in Paris (OK she does have a little help)
Fine and mellow Billie
Ella
And just to switch it up Hurrah for the Riff Raff
I wouldn’t say there is more emotion just different emotions. Ella has a lilt of happiness as a compared to the sadness Billie portrays.