Nobel Prize for Literature goes to Bob Dylan

I agree with this but this mostly also has to do with the nature of the music itself.  Many Johnny Cash songs are also like this (the difference being Cash has a much better, way more powerful voice). Yes, anybody who can hold a key can sing Dylan but it is also not possible to sing these songs any other way.  Jeff Buckley covered one Dylan track; horrendous, oversang it to death. I don't believe you could ask Dylan to suddenly stop singing gentle country-rock and perform Script for a Jester's Tear on stage but he wasn't even trying anyway.  Also, even John Lennon is only a little better that way.  Anybody can sing Imagine or for that matter most of the Lennon-rendered tracks on Beatles albums (at least Macca uses something that could be called range).  Lennon just gets away with it because his voice is more pleasant than Dylan.  There are plenty of celebrated but fairly mediocre/average singers in rock.   

Yup, front of face is dead on right.  You can't produce that Stevie like bright, sweet tone without feeling the resonance in the 'mask' as it is called.  He uses it a lot in his singing and not always when going very high, even in mid fourth octave notes.  So does Klaus Meine and it is much more pronounced in his case.   

I think most Dylan songs benefit from having someone else sing them, but that's just my personal view. 

I don't think it is musically irrelevant, without the music it lacks a dimension that "traditional" poetry carries, with any song (whether by Dylan or anyone) the two go hand in hand not because that's how we are accustom to hearing them, but because that's how they were created. It is rare for a lyric in printed form to leap off the page (in the way that a Byron or Hughes poem does when we read it) unless you know the tune that accompanies it.

Well, as long as it has melody (and Dylan songs do have discernible verses even if they seem to almost run along in a procession) and is performed with the help of musical instruments, it is still music, very much so. I get that you don't like Dylan (and I don't like the music either) but I can't say a song like Blowin' in the wind is just poetry recital, it does have a melody.  It just doesn't have the elegant shape of a great melody like Whiter Shade of Pale.

That's simply because the lyric was written with the musical accompaniment. The song-melody line needs the underlying bass and/or rhythm line accompaniment to make musical sense and vice versa. It's quite difficult to explain what I mean by this, (but it's in practically every Beatles song - these songs were written by two musically illiterate writers and "break all the rules" yet when you look vertically through each song, from sung-melody to guitar accompaniment no rules are actually broken), in these kind of singer-songwriter songs the tempo and rhythm moves melody along on the horizontal axis but the harmonic content of each beat is resolved on the vertical axis - it's like (figuratively but not literally) a nice harmonic chord in the song becomes incomplete if you remove a horizontal layer from the recording. Dylan isn't unique in this, a lot of lyricists who compose at the piano or with guitar in hand work in this way and you'll notice that the rhythm of the accompaniment stays in step with the lyric whereas songs written separately don't always do this.