I disagree, and I think the lack of exaggeration is the very thing that hinders those who don't get it. Most contemporary movies hit one over the head with crude humor and/or action that is well beyond believability. The humor and contrasts of this movie are subtle. The scenes are believable. I have known people like some of the characters in the film; I expect most people have. And I think the films’ charm comes from the goofy displays of ineptitude from characters who are not necessarily stupid – blind spots on parade… With the exception of the cow scene there are few belly laughs, but it is a funny film that just keeps growing on you.
My sons and I had a similar experience with a much worse and different film; UHF. It is corny, and Weird Al is a terrible actor – the worst of the film. But the goofy scenes and catch phrases grow on you. Watch it a few times and when one of your kids has a Napoleon moment you too will be telling him, “STUPID! – YOU SO STUPID!”