no, being soulful doesnt mean only using bends and vibratos, but it's part of it... speedy players dont use those much, and that's why you can hear only meaningless notes all the time... it reminds me of the piano, actually, where you can't do all the stuff you can do with a guitar.. it's hard to me to explain myself but in guitar playig there's a term called feel, which is something that certain people have and others dont.. i can't tell you exactly what it is, but part of it is how you playing.. and i think that when you mostly concentrate on speed you loose big part of it, for example in the stairway solo, there is a part made of thriads or whatever it called, it's played on the 15,13 frest on the B string and the 14 fret on the G string, and when page plays it he's doing it with a bend of the 15 fret, and this is a part with a great feel, but if someone like vai would be doing that solo, probably the bend was left out, and instead we would get a faster playing, but the triad was loosing its meaning...

it's really hard to explain exactly what i mean by bends, and vibratos, but i trully believe that blues based guitar is the only soulfull guitar playing.. yet it's only my opinion