The only thing about including Dylan (or any of the others) is that it knocks someone else OFF the list.   It's saying Bob Dylan is a BETTER singer than Joan Baez, KD Lang, Luciano Pavarotti, Nat Cole, Jo Stafford, Marty Robbins, etc., etc.   

A month or two from now I'm sure no one will care.   For that matter, if they did the whole process over again right now, I'd wager they'd come up with a very different list.

I just think it's more than a bit of a misnomer to use the terms "singers" and "of all time" when their own (detailed) description shows they're really rating musical artists on criteria such as songwriting ability and all-around entertainment value, plus they're clearly leaving out well over half the world (culturally and geographically) and half the musical genres where one might find great singers.

It's about as meaningful as People Magazine's annual "50 Most Beautiful People" list - except that that list doesn't purport to represent "all time." ; D