" I don't know if I've ever heard anyone who I'm sure changed a traditional song just to get noticed or for personal ego."

Oh, I have! I doubt they'd admit it, even if they realized it...but I could make a list. (I started a thread about the song "Hard Times"(come again no more) a couple years ago to illustrate this very point. And I recently was listening to many versions of "The Two Magicians" in which 'sound effects' almost obliterated the story.)

I quite agree that Doc Watson and those others just 'liked music' and played whatever they found interesting....but I feel that Doc in particular 'felt' the differences and could easily tailor an LP or concert to fit his audience. You were never in doubt it was Doc, but the feel of the music usually was quite consistent with its origin(s).