American Beauty is a satire on "the American Dream" as it stood in 1999, and it can very well be used as a "benchmark" on just how far American "lifestyle" has come [or in fact GONE] since Death of a Salesman and Lolita 50 years before.
The main issue in focus is the Death of the so called Nuclear Family but a very tasty side dish is the changing "values" [or lack of] in sexual matters, both parents and kids, and here I am dealing with the kids issues.
But I should first explain that the very important ["Freudian"] question of "Wild Oats" presented by Nabokov in the Lolita book as to why Humbert became as he did is glossed over in the movie. That was done by agreement of Kubrick and Nabokov purely to reduce movie length, so we are shown nothing of how Humbert almost went out of his mind missing his Wild Oats with Annabel when he was a teenager himself.
So movie starts in the "enlightened sexual times" of 1950s when in real life sex was exciting, waiting to be discovered, magical, vivacious and most of all FUN, albeit on screen the The Hays Code essentially prevented any suggestion that sex even existed. Lolita was however made despite this dichotomy and it was the combined skills of Kubrick and Nabokov that allowed them to show Lolita [and her men] in the full glory of the ACTUAL time.
As an example Lolita was able to seduce Humbert simply by playing out a fun "game" and Humbert simply lay back and enjoyed it, or as E Annie P said in Brokeback Mountain, "no instruction book needed".
At this point I will attempt to define the Wild Oats Laws by saying a person [perhaps moreso a male] MUST get a wild, uninhibited, exciting introduction to sex [preferably in a haystack etc] by their mid teens OR it will eat the livin' shit outa them more and more as they try at 27, 37, 47, 57 or 67, getting more pathetic and desperate as years go by. This is what Humbert KNOWS but is powerless to remedy his mind by such things as using prostitutes and getting married [and divorced].
ie he learns there is no way that simply "getting/buying" sexual acts gives one their Wild Oats [and of course Kubrick nails this in Eyes Wide Shut with the depraved old wrinkly Jews watching sex from behind their Fidelio masks]
So once he sights Lolita's cherry pies he is hooked on a course of action that ruins his life - such is the curse of Wild Oats deprivation.
fast forward 50 years
Lolita [Haze] suddenly morphs into Angela [Hayes], both names purposely intended to mirror Hays.
As Angela, Lolita has lost all semblance of "sexiness" and has simply become a "sexual object" in the great glorification OF sexual objects [ie Porn, pronked as Erotica] in the American Beauty.
The takeover of the education system by the small f feminists in 1970 has seen that Angela has been "Carefully Taught before she was 6 or 7 or 8" [South Pacific 1958] all about reproduction in a stiff, starchy, academic and moralistic way that has removed forever any chance that "sex" for Angela could possibly be exciting or fun, but rather, as Angela relates, sex has been "commodified" and has a monetary value along with all the other "stuff" in the American Beauty.
But most of all this has meant Angela has totally missed her Wild Oats and is in fact totally frigid, the exact opposite of her fantasy world where she expounds her totally liberal "virtual sex life" to anyone who wants to listen, thus reflecting the fantasy world of the founder of the small f feminist movement Germaine Greer, with her fascination for Catherine from Jules & Jim.