I'm actually going to say this nonsarcastically. In its defense most of the movie is still pretty funny, but the eugenicist intro is really bad. It would've been better if you'd chopped that off and said he'd just been isekai'd to a world of stupid people.

Really though I'd say the part that's aged worse is maybe not even the film itself but the way that people keep trying to compare it to the present day. Idiocracy is a world of well-meaning idiots who still have hearts of gold, and the day is saved when they step aside and let the smartest guy in the room figure things out. That is the exact opposite of the problem we're facing today, where the villains at the top are very smart and very evil, smart enough to know how to use stupid people as puppets for their selfish aims. Idiocracy doesn't even have any true villain in it.