Some good points Blackcatter.   I do remember something that Utah Phillips once said, and this is not a direct quote but to the best of my memory - he said that nobody "owns" a song - once it is written it is out there and everyone owns it. I agree with you about the different versions of Bogle's song. I don't care for the Baez version either.   But every now and then I can appreciate a Krispy Kreme dougnut as opposed to the Dunkin Dougnut version.

They aren't modifying someone's piece of art - that art still exists in the artists vision. They are creating something new - and it isn't meant to be an improvement, just another vision.

Woody Guthrie never wrote an original tune. As Arlo has noted, Woody felt it was best to take an existing song that people know and create new words if he wanted someone to start singing his song. Sort of gives the audience a head start on learning the song.

It isn't right to take someones art without giving them credit and/or financial consideration.

With all that said, I too prefer the original versions - Almeda Riddle is someone that more people should be listening to. IF a new version of one of her songs creates an interest, or even an awareness of her body of work, then I think the project has succeeded on a secondary level.    Often I will hear an artist "cover" another artist's song, usually someone that I haven't been familiar with.   It will cause me to search out that artists and hear more of what they had to offer.

This is a complicated issue.