Having a good voice is quite obviously not the same thing as being a good singer. Do you rate every owner of a Martin as a good guitarist? I recall Don Firth on a singing thread quoting his voice teacher on Caruso, "Like hearing a Stradivarius played like a baboon". It's what you do with those vocal chords that matters - and for me Bob Dylan makes the right kind of noises.
I am also baffled as to how one can describe the author of Blowing in the Wind, Ballad of a Thin Man, I'll Be Your baby Tonight and Mississippi as a one dimensional artist. Martin Gibson, you must have some harsh words for Cole Porter...