Anybody who likes rock and punk rock knows Green Day. From Dookie to their newest album "Tre" the one album that has stood out to a lot of people is American Idiot. Why though? I mean, it was adopted for Broadway so what makes this album in particular so popular. Also this doubles as a Green Day discussion topic so let's talk.
I think it's supposed to be a coming of age story of the Jesus of Suburbia mentioned throughout the album. I believe Wikipedia has something about this.
I suspect it was largely a matter of timing. It touched upon some political issues that were very contentious at the time (and still are), and also kind of fed into the post-9/11 cynical feelings a lot of people had. Plus, it has a decent amount of variety and some really catchy songs!
As for Green Day in general: though I don't always care for their lyrics/messages, my favorite album of theirs is 21st Century Breakdown. I have a thing for rock operas and albums that have a lot of variety on them. American Idiot is a close second. Most of their earlier albums are too heavy for my tastes, though there are a few songs I like. And the recent "trilogy" of albums seemed to have a lot of filler.
American Idiot became so popular, in my opinion, because of the ongoing story that it told through the songs.