Were they really? Here in France, when you meet a woman you kiss her on the cheek, but when you meet a man you shake his hand; you use different pronouns ("vous" or "tu" - cognates to "you" and "thou" in English) depending on the relative status of your interlocutor (and other things); in many western countries (the US more than France; though it seems) it still seems expected for a man to buy an overpriced piece of rock to the woman he's planning to marry and not the other way around, etc. - we have plenty of rules that depend on gender! (probably more than on class)

Is it a social blunder not to kiss a woman on the cheek when you meet her? On the same level as asking her out in an elevator at 4 AM? To be honest I'm not sure how strict the rules of etiquette were in the old days, but I think there's a distinction between customs and etiquette. Customs are things most people do and are comfortable with and no one really objects. Not following expected etiquette causes discomfort and potentially emotional harm.

I wonder how much influence etiquette has on a man buying a diamond for a woman and how much influence marketing has. In fact, I wonder just how much of our current etiquette (or at least our customs) has been caused directly by marketing and popular entertainment. I suspect we treat each other a lot like we see people being treated on TV and in movies, rather than how they would like to be treated.