According to Janie "There is still 'magic in them thar hills.'" which would seem to imply that some areas weren't scrubbed as thoroughly on the Washboard of Religion...IF that's what brought on the shift.

Maybe after a generation or two, songwriters didn't put in mystical stuff--because it wasn't such a part of their lives..and with that trend, they could easily have begun the process of 'updating' the Old Songs.

When everyday life is scary, hard and exhausting, scary songs might have simply lost their appeal. Isn't that what happened with Fairy Tales?

What did the songs change to?
Did they go from "you have no control over this situation" to "fork in the road" type where the character had to choose which way to take their story by their response toward the song situation?