I don't know about requests for obscene versions, but I do know that - in England at least - it's always wise to move down market if you want to shift stock. See any nice new restaurant and go back a year later... and a year after that. Everything moves down market until it becomes acceptable to the masses, even if the price remains as high!

In song, therefore, I see no reason why it should be different.

These people are The Folk. How can we say they're wrong? ;0)

More seriously, there are things which spoil good songs. Daft alternative versions (of which I've written a few) can spoil people's enjoyment of the original.

As soon as a song is seen ironically, then it can no longer be taken seriously. Is The Wild Rover really a substantially worse song than any number of other mediocre/banal folk songs? Yet it has this special place as "The Song Not To Sing" if you are " a real folkie", and "The only folksong we know" if you are not a folkie, but just a "Folk".