a fel33 :Homogeneity, uniformity, consensus, profit, propaganda. Not in that order. The likely cause was a combination of modernity's obsession with sterility, arbitrary personal transformation without actual meaningful change or growth, and to make or grow a market and a demographic. In this case, it was probably influenced by the various corporations that sold personal care and beautification products largely to women(at least, back in the early half of the last century)coupled with the porn industry's shift from being an afterthought of the arts to a titan of industry and a vice as American(or relatively harmless) as apple pie and beer.