That people used the word 'niggering' in the 20th century doesn't prove that this was what was orignally intended by the black-face, rather it is equally possible that an older black-face tradition was being described using the terminology & culture of the day. Just as some racist people use 'thieving arab' as a term of abuse, it doesn't mean all arabs are thieving. A contemporary description or word for something does not constitute a things definitive origins.

Regarding the tunes, no-one knows for definite what tunes were used by border morris dancers, but amongst them appear to be country music, "schottisches played rather slowly", and yes a few minstrel songs, because I suspect (as has also been recorded) that most of them played songs that they liked. In the same way our own tradition of folk song is historically replete with murder, incest, racism & the like - does this mean that all modern folk song is built upon an inherently racist foundation?

As to the two quote thing, if you scroll up the thread you will also find quotes from indivduals who didn't find it offensive. Thus as it is a matter of perception, surely education as to intent is the key rather than starting blanket bans.