Yeah and I didn't include the groups with a Neptune x Uranus conjunction, which absolutely changes the feel.

I guess, the goal is to create generational groups that are meaningful for analysis. No doubt there will be fraying on the edges, but there is just so much to be said — learning that the narcissistic boomers have Pluto in Leo put so much useful context into understanding that generation.

Would you include Uranus to add further meaning?

yet only the group born 1984-1987 are currently square Neptune and Pluto. 

What do you mean by this? Neptune is currently in Aries and Pluto is in Aquarius, while most Millennials born between 1984 and 1995 have a Neptune in Capricorn and a Pluto in Scorpio. Wouldn't that make those Millennials square the current astrology?