The thing that bothers me about most contemporary praise for Idiocracy is the failure to view it through the appropriate historical lens, and so most of the praise ends up being shallow in the retconned context. Idiocracy was created in a specific time period—the same one that American Dad! was born in. (NB: "born" being the crucial word in the previous sentence.) It's possible in 2021—or 2011, even—to have watched and enjoyed both for the first time and still not understand why either were created.
I'm seeing more references to Idiocracy now on social media because of Don't Look Up's recent release (compared to, say, how frequently Idiocracy was mentioned last month). There's a lot of problems with Don't Look Up that make for it not being an example of greatness or even very-goodness, but one thing in particular in comparison to Idiocracy are the movies' protagonists. In Idiocracy, Not Sure is a pretty average guy—maybe even a little dumb. This is what the writers of Don't Look Up missed out on. Idiocracy is smart people writing about about a dumb-to-average "hero" because the egos of those involved (the creators and their audience) don't require him to be bigger than they are. In contrast, Don't Look Up is a movie written by people who are as smart as Not Sure is dumb, trying to write for characters who are supposed to be smarter than the writers themselves and the people who are supposed to enjoy the movie the most.
Some reviews called Don't Look Up smug and sanctimonious—and they're right. With Idiocracy and Don't Look Up, the humility and lack thereof, respectively, when comparing the two accounts for a lot of why Don't Look Up is worse than it should be. (Given what Don't Look Up tries to do, it should do it better than Talladega Nights does, for example, but it doesn't.) Also accounting for a lot of what made Don't Look Up a not so great way of cribbing from Idiocracy is that Idiocracy was taking aim at the zeitgeist, whereas Don't Look Up is a very safe movie to make.