Hey, the Starship Troopers movie is definitely more than fun, dumb SF. A chilling examination of both the vapidity and allure of militarism, like a lot of the best SF its primary aim is satire.
Like with anything, I think the PEST model can work as a starting place, provided that the map is not the territory and a lot of the choices SF authors make don't always fit neatly into these categories. What about my all-time favorite SF movie, Children of Men, where the political, economic, social, and technology have all undergone detailed changes, but the main difference here is biological (people can't have babies). Or my all time fav SF series, Book of the New Sun, where the major change is that *take deep breath* it's a million years in the future and aliens working for the Judeo-Christian God are slowly killing off humanity and the MC is objectively the messiah but also a liar and kind of a sociopath and had superpowers that can change reality but oh yeah other characters can change reality too so you have no idea what's real or not at any given moment. Or VALIS, where the major change to PEST is that the actual writer Phillip K Dick is having a nervous breakdown and trying to fit his gnostic worldview into a loosely organized jam-sesh.
Not to say I have a problem with this perspective, I see what you're offering here is a toolset and not a GUT of sci-fi writing. I think some of us might approach things from a different perspective, just as many of us may go outline or no outline.