In "Starship Troopers" the book, a trainee asks why they are learning to throw knives when they have nukes. The instructor stops the drill, and points out that you don't housetrain a puppy by decapitating it. The military is supposed to used controlled force to achieve policy objectives, not wanton destruction. He tells the recruit who to talk to if he still doesn't understand.
In the movie, the instructor throws a knife through the recruit's hand, and says, "Hard to push a button now, eh?"
I get that the movie is satire. I even get that there's a lot in the book that can be fairly satirized. The problem is, the movie is lazy, unfair, incompetent satire.
That's why I said you had to basically overlook all the criticism that either omits things from lines or takes them out of context. If you do that then it is a decent movie. If they re-did the movie from the standpoint of "why you fight" and "violence as a specific means to an end instead of mindless killing" it could be a very poignant movie. Especially considering the current climate in the US with the recent withdrawals from Iraq/Afghanistan and as evidenced by the success of American Sniper. It would be like the 1st half of Full Metal Jacket plus Platoon without most of the anti-war stuff(going from not sure why you are fighting to realizing the why doesn't even matter in the first places, you fight for survival and your buddies), in space.