Change happens....that is inevitable. I just wince when I hear 'change' that is mostly about the performer, and not about the song. So many performers seem to approach music with an attitude of "I'll never be noticed unless I do something really 'different'.....and I really want to be noticed."
In pop music this is standard procedure, but one of the fundamental aspects of 'folk' and 'traditional' is to engage and preserve our heritage, and when traditional music is gratuitously changed just to 'identify' the wannabe performer, a lot is lost. No law agin' it, but it seems to me a shame to continue to call it 'folk' or 'trad'.

As Jerry suggested, vague categories "... would create chaos in a record/CD store."

Making a song your own is part of the 'folk process', but setting the folk processor on "puree" just makes it hard to identify the ingredients.