Some groups (in the US) are actively trying to ban teaching it (or some definition of it) in school and some groups think it's essential learning. I'm guessing most have no idea what actually was or wasn't being taught, but that's another issue. The point here isn't whether they're right or wrong to do so it's that obviously education isn't "neutral territory" or something the country is comfortable leaving to the education community. Creation/evolution is the "classic" example of this.
As soon as you try to do media studies or critical thinking at scale somewhere in K-12 someone is going to think that you're doing it maliciously to advance or attack a worldview and it's going to become a mess. Another commenter mentioned letting kids dissect Fox and CNN - how long before those kids say something to their parent that Really Believes one of those channels and that parent goes to the school board with a mob of other Believers? Or someone tries to get a class started or teach a class that claims to be critical thinking but focuses all its time on the flaws in a particular perspective?