This is my theory based on anecdotal evidence I acquired as a temp slash consultant, and is something I've been drumming on for a while.
First, however, I feel that the media landscape hands out generational labels too haphazardly. To me, its the decade your born in, that says more in our quickly changing landscape... Born in the 50s is boomers, 60s is Generation Jones, 70s is Gen X, 80s is Gen Y, 90s is Millennial and 00s is post-millennial. In each group there are subgroups that have more affinity to preceding or later groups.
That said, boomers seem to think its possible to call Gen X everything from 1962 to 1985, and Millennial from 1984 to 2000. The fact that they are happy to rearrange groups at a whim to fit with their observations. Look - she has a social networking accounts, she must be a Millennial, look he has teenaged kids, he must Gen X, and so on. Its lazy and tired because they still don't see what the real generation gap is: Access to success.
Gen Jones was entering the workplace in the 80s, learned how to use technology in the workplace, and successful members of that group are forward looking in tech. They would be the oldest group that en masse has a presence in video games. Gen X had access to computers (depending greatly on socio economic status and interest) and the members who embraced change became the people who saw a future in technology and technology enabled startups, like dot coms. Generation Y saw ways to new things with tech. While Gen X replaced traditional services with internet based services, Y invented wholly new paradigms, and embraced social networking, while X largely replaced traditional services.
Millennials grew up in this landscape. Constant and rapid change. But this where the real gap is seen between Boomers and the rest: The boomers are unable to embrace that change. They are angry at change. They are more likely than any other group to retain their 20th century technology standards, they are hooked on broadcast tv and cable. They write opinion pieces trying to say that video games aren't art, eBooks are just a fad, and social networking as useless, and smart phones make people antisocial.
And they are such a large group that their opinions matter.