The adults vs. teenagers is always a good theme, and I'm surprised none of the past Legion writers have ever touched on this. The series is remarkably counter-culture and that's probably one of the reasons that readers really seems to connect with the new series.
I like the theme too. BUFFY THE VAMPIRE SLAYER was predicated on three premises:
1) Youth and new ideas always are preferable to age and tradition.
2) Authority figures are evil, and rebels good.
3) People that cry loudly about their own morality tend to be the evilest people of all.
But I take exception to the notion that Waid invented this conflict for the Legion. He is, though, the one to blow it out of proportion by placing it alongside an incongruously dystopian future.
The Legion's Youth Rebellion originated under the Shooter run. There, they go to planets filled with scowling mindcontrolled grownups keeping kids from sharing malts and doing the Venusian Sock Hop. In "The Outcast Legionnaires," (1967) the Legionnaires were youth rebels against a Universo-controlled cosmos. Later, we got the Legionnaires battling Mantis Morlo's pollution factories, which threatened the universe. "Counterculture" among the Legion is nothing new and certainly wasn't created by Waid.
So, this run is getting "raved reviews," eh? As a personal aside, nothing makes me more sad than the cultish, personal devoted following of terrible, untalented creators. If Waid, Ellis, Morrison, Bendis, Byrne, and Giffen want to be terrible, it is tragic but they are the failures of only one man. If these same men can garner hordes of bobbleheaded robot supporters, it is a failure of the human race. It was P.T. Barnum that said "nobody ever went broke underestimating the intelligence of the American public."