Just my 2 cents, but I'd put the ubiquity of spats among the well-heeled in the 18th and 19th centuries (and their extinction in the 20th,) down to one cause; the amount of horse manure in city streets (and we think we have 'vehicle exhaust' problems!)

The cost of replacing/cleaning spats would be so much less than than replacing/cleaning shoes that got a load of exhaust down in the laces, tongue and ankle areas.