Roberto:

You are right, of course; Graves' interpretation is fascinating, as is the difference between the Irish, English and later American versions of the song.

I think the elegance of the tale, even only as a love story, is enough to explain it's survival. It has persisted in versions that have no reference to the witchcraft, or the laughing cruelly.

My sense is that it is an archetypal picture of hardheartedness in the face of love (whatever the reasons for it) and that the appeal of that image reaches anyone who has either experienced or engaged in that hardness.

In the final analysis, to my mind, the tale shows the tricky web that gets woven when humans choose not to communicate when they really have something important to say.

A