I'm sure I've seen a study which showed some evidence of blacking up prior to the minstrelsy period, but this is on another computer and I can't access it. It is also relevant that prior to the same period blacking up was illegal under anti-poaching laws. When these laws were repealed morris teams may have simply resumed blacking up without necessarily being influenced by minstrelsy which justhappened to be introduced around the same time.

Minstrelsy was indeed a huge craze during the same period as morris, but correlation does not necessarily imply causation - this is a well-known "trap" when looking at data. Because minstrelsy was so popular I find it significant that blacking up was not more widespread in morris, and it seems to been found in the traditions most associated with begging customs which lends support to the disguise interpretation. My own conclusion is that minstrelsy was not the origin of blacking up in morris, although that those traditions which already blacked up (or which used to before the Black Acts) naturally adopted more of the trappings of minstrelsy than those which did not already do so. I accept this is only conjecture of course.

I don't think we should be ashamed of our traditional customs which involve blacking up. If teams or individual performers are uncomfortable with it and decide to do something different that is their choice, but I don't think they should be forced to, and especially not by violence or intimidation.