My suggestions are based on programs about the regimes of the workhouses,people were treated harshly to make work more attractive than living on the parish.
Because the parish had to support the poor they saw them as parasites.   
The same attitude was directed to begging,because Morris Dance was not regarded as proper work that was seen as begging.
Your reference to blacking up before 1750 shows it happened long
before the black minstrel shows.
That form of entertainment was an American idea which came about when
Slave based music became fashionable but unacceptable on the stage.
The way round it was for white artists to black up and perform it instead.