Theodore Dalrymple writes about Minding Our Manners:
The argument goes something like this: formality is etiquette, and etiquette is a manifestation of an unjust, class-ridden, patriarchal society. The rejection of etiquette and the formality it entails is therefore a sign that one is on the side of the angels, that is to say, of the egalitarians. Modern egalitarians, at least in Britain, do not content themselves with the kind of abstract or formal equality before the law that allows any amount of difference in wealth, status, taste, and sensibility; they demand some progress towards equalization of everything, including manners.Of course, egalitarians are just as attached as everyone else to their own material possessions and wealth and have no real intention of forgoing them by radical redistribution, at any rate, of their own money and possessions. The struggle for equality—of the actual rather than the formal kind—has therefore to be transferred to fields in which it will cost the egalitarian nothing, or nothing material and financial.
What better way to prove your egalitarian credentials than by adopting the supposedly free and easy, utterly informal manners of those at the bottom of the social scale? The freer and easier the better, for such informality demonstrates another quality beloved of, and praised by, intellectuals: a superiority to the dictates of convention. Thus you can never be quite informal or unconventional enough.