I hate 'em. Yet all war movies have them, and it would be near to impossible to make such a film without them. Cliches and type-casting are frustrating, yet here to stay. And, much as I hate to admit it, when correctly used, they can be a real asset to a filmmaker.
Let's start with cliches. Here's one that makes me nuts: the binocular matte. You know the one; it's a figure-eight on its side or infinity symbol that lets you, the audience, know that we're looking through binoculars. The problem is that if you've ever actually looked through binoculars, you don't see what you're looking at in a figure eight. You see a circle.
However, if you wanted to correct this error in a film sequence, you'd need to do some explaining to your audience so that they'd know you're looking through binoculars. We have been trained by films that the matte=binoculars. To retrain the audience would take time and effort better spent on doing what films are supposed to do: tell stories. So this cliche, like many others, are a short-hand for the storytellers to communicate to the audience.
Another war film cliche: You can always tell the star of a World War II film as he will always have a different weapon than everyone else (and it will likely be a Thompson). Again, quite unlikely in real life, and again, short-hand to the audience that here is a character to whom you need to pay attention. Oh, and he's going to lose his helmet real soon so you can be sure to see his face.
What about type-casting? It's certainly very frustrating to actors. Our own Captain Dye is certainly frequently type-cast. I call him 'Officer Exposition.' Here he is in Act 1 to point at maps, give orders, and explain the jeopardy. Bye! See you in Act 4, shaking hands and congratulating everyone.
Alfred Hitchcock observed that when the audience sees a star, they know who the hero is, and the director doesn't have to spend any more time explaining that. Once again, we have a short-hand way of communicating information that would otherwise take time away from storytelling.
Like any tool, it's neither good nor evil; it's either effective or ridiculous. Smart directors know the value of these tools, and when to throw them out the window. A final example from Mike Mayo's terrific book 'VideoHound's War Movies:' The Nazi officer in the long black convertible, driven by a chauffeur with the top down. American officers don't do that; they're always in the front seat of a Jeep, either next to a driver or driving himself. What's the shorthand of these images? The Nazi is arrogant, haughty, and feels superior to everyone else, but the American is a common man in a common vehicle.
The terrific comment on these visual clichés comes from a brilliant turn in 'Schindler's List.' Amon Goeth (Ralph Fiennes) is riding in the back of an open convertible, and it's snowing. He asks, "Why is the top down? I'm fucking freezing." Even the brilliant Spielberg understood the need for the cliche, even while commenting on its inanity. Perfection!