] The decline of powder in England had quite a bit to do with the tax of on powder:

I think that was more-or-less the last straw, rather than the main incentive, and if the politicians had had any fashion sense whatever they would have foreseen what would happen (but fashion sense is not usually a requirement for politicians).

The early stages of the French Revolution were probably the main incentive to get rid of powder, Robespierre being almost alone among the revolutionaries in keeping his head powdered until it fell.

However, even before the French Revolution, there were some notable unpowdered heads. Benjamin Franklin is the most famous, but there were others (see the link to an unpowdered military head painted by Reynolds in 1782)