I'd say you can't make this stuff up, but Mike Judge made this stuff up before it was real life!

The Bush era—or rather the core of the era, from about 2002 to 2007 (i.e. after the dust from 9/11 settled and before the housing crisis), was a boom time, and much of the future situation feels like it comes from "what if this boom lasts forever?" (i.e. society becomes wealthy enough to automate everything, so people just sit around and watch Ow My Balls and drink Brawndo every day instead of having to work). Something made nowadays would probably start with a premise that comes from "Millenials can't afford anything".

Mainstream culture during the Bush era was also before the sudden explosion in nerd culture. Superheroes hadn't eaten the entertainment industry yet, nostalgia wasn't yet a driving force in pop culture, and it was still uncool to admit that you enjoy RPGs or reading comic books or doing whatever else nerds do. A parody of modern cultural memes would resemble Ready Player One more than Idiocracy, and Ready Player One wasn't even intended as parody. Instead, Idiocracy spends a lot of time lampooning shock reality TV (e.g. Ow My Balls), which was a huge thing in the mid-00s with shows like Jackass and Fear Factor but isn't big anymore. And the general culture is different. Like, you had people saying things like "you talk faggy", which sadly was common in real life during the mid-00s, and as such it was a ripe target for parody, but would be completely taboo now. Even in bro-culture you wouldn't see that in 2018 (I mean, there's still a lot of homophobia around, but you don't see those slurs dropped casually anymore), and so a parody of modern bro-culture probably wouldn't even mention it. TBH, a parody of modern bro-culture would probably involve MRAs and redpillers and pseudo-intellectuals who worship Jordan Peterson.

Like, the _idea_ of a movie about the future being full of stupid people would still be relevant in 2018 (and you can thank Trump for that), but it wouldn't be Idiocracy because Idiocracy was more about parodying mid-00s pop culture than anything else. I'd imagine a late-10s Idiocracy would involve some combination of nerd culture turned mainstream eating the world, '90s nostalgia (with "only '90s kids remember" somehow being reiterated over and over 500 years in the future), avocado toast, and nobody being able to afford a house.

But...they are (or, rather, they can reasonably be expected to produce genetic changes which reinforce themselves.) Because cultural changes effect mate selection, and also otherwise improve the relative fitness of those naturally inclined to thrive in the cultural environment.