Of course it's a wild generalisation, which is why it's useful to demographers (as well as marketers) I'd have thought. Like it or not, people within a generation are more likely to share social trends, attitudes, outlooks, than one generation is with the one immediately previous or subsequent to it.
I bought a cassette tape recorder about a dozen years ago when I was working as a journalist. Unpacking it at home, I was horrified to see that it had Genexxa emblazoned on it. I suppose when I undertake the chore of buying appliances I'm focused on their features rather than whether they have a dismal, cheesy name.
This term, by the way, was popularized by Douglas Coupland's Generation X: Tales for an Accelerated Culture (1991), though the term actually goes back to a 1964 British sociological study of teenagers (in the mid-1960s, so this was the first wave of the Baby Boom generation), written by Jane Deverson and Charles Hemblett and also called Generation X, I'm guessing because the post-WWII generation seemed like such a mystery to their elders.
These terms - Generation X, and Generation Y (Why?), and now Generation Z – seem so contrived to me, quite patronizing (they are all essentially marketing labels), and, needless to say, so unimaginative that I feel sorry for the people who assume these terms for themselves.
These dates are floaty, I think. The U.S. Census Bureau considers a baby boomer someone who was born during the demographic "birth boom" between 1946 and 1964. It seems that everyone I talk to has seen or read different dates! :-)