The propaganda was part of the joke.
Someone who didn't understand satire would have thought Team America was taking a jab at all the countries the US has "helped". In reality it went after everyone.
The same is true about this one. The intentionally bad acting, unbelievable plot and action sequences, and the over the top propaganda was taking a jab at Hollywood just as much as the border militias. This is really the fundamental theme of modern grindhouse movies.
They're fun to watch as long as you can shut off your political logic and lock up your inner film critic for an hour or so.