Absolutely. What happened to Generation Y? If Gen X cuts off at 1980, wouldn't Gen Y be from 1980 to early/mid '90s? Millenials are kids who don't remember dial-up, and perhaps even wired ethernet.
Also, I very definitely remember dial-up... and cassette tapes, and VHS, and walkmans, diskmans, CRT monitors, playing outside, etc :)
And when kids do play outside their parents hover over them and they can't explore or take risks.
Speaking purely from the perspective of someone in the US. I know other countries are very different.
Generations tend to be around 20 years and every one has a big gap between the start and the finish. Just look at baby boomers, do you think someone born in 1946 with a returning GI father and graduating high school right into the start of Vietnam escalation had much in common with someone born in 1964 and not graduating high school until the Reagan administration?
Regardless, although I understand the ubiquity of terms like millenial, I think there's so much more value in breaking down things into decades. I'd actually say 8 year segments are the most useful because you can use presidents (who often serve 2 full terms) as references, but that's specific for the US and doesn't jive well with a base-10 counting system.
I bet out there somewhere someone has come up with a great way to classify generations specific to cultural changes and I just haven't found it yet. Maybe it'll show up in this thread.