The thing that fascinates me about AGT is how it represents (or seems to represent) a throwback to the old studio system of Hollywood (I realize that this has been building for some time in these types of shows, but it seem particularly apparent in AGT.  The acts are straight out of Vaudeville, and I’m not just looking at the auditions.  In the Top Forty this season there were/are a magician, an impersonator, prodigies and virtuosos of several stripes, freaks & (old school) geeks, comedians, weirdos, children and dogs along with the more popularly expected singers and dancers.
Along with the throwback nature of the acts, the networks have *finally* figured out how to make appointment TV work, and it’s not with the voting (though that’s certainly very important).  The nature of the acts themselves emphasis the artifact of the singular performance.  American Idol has nothing but the voting dynamic to create the need for immediacy, because the individual performance of the song is fairly indistinguishable, in terms of dramatic value, from original broadcast to rerun to Youtube clip to cd release.  But magic acts or acrobatic dance acts or virtuosic piano acts or glass chewing acts or chainsaw juggling acts or burlesque acts contain within themselves drama as *performances*.  You see a magic trick once before you start to analyze it (this particularly comes out in the YouTube clips of the Drew Thomas Magic acts). With geek, chainsaw juggling or other death defying acts, you only really watch it once, and when they’re not dead by the end of it, you don’t need to watch it over and over again (unless you’re showing it to your friends). The drama of the performance is diminished once you know they don’t drop a saw on their heads or choke on a lightbulb.  Virtuoso and acrobatic performances are of a similar species (will they succeed or crash figuratively or literally), ad similarly the value of the act is in the artifact of the individual performance, not in the value of the act itself.  
So so far we have two major throw-back elements, both in the types of acts and the live-performance-heavy-nature of the acts themselves. The final throwback element I see is in the prizes.  The million dollars is by now fairly standard, and by current economic standards pretty paltry actually.  Moreover, that is not what the acts are focused on, as shown in their individual interviews.  The acts focus on the prize of a show on the Vegas Strip.  Vegas is a throwback city, in terms of morality, in terms of the kind of entertainment available there, in terms of the sheer scale of the  place.  It calls up associations of the Rat Pack, The Godfather, Prohibition, deserts and oases both, and a delicious disregard for the consequences of actions.  The prize could just as easily have been a show in Carnegie Hall or in LA, but the producers specifically chose Vegas.  
Unlike most reality/competition shows (and I am hesitatingly including American Idol in this category) AGT is not a 15-minutes of fame show.  It is about the old studio system, where small town talents were “discovered” by studios and hand reared to fame, fortune, and life-time exclusive contracts.  The dream being sold is not “You too can be on TV and get paid 100k to eat a bug.”  It’s “You too can be an entertainer (NOT an artist), because we are opening up the studio system to you.”
I’m also fascinated that none of the judges are actually American.  But I’ll leave that for another entry.

EDIT: David Hasselhoff is American. For some reason I thought he was German.