I believe that this topic is just part of a larger picture, which I will try to address with my own views. In my opinion, I believe that many Christians seem... obivious that there are other important things in this world besides God. He is certainly the most important thing, but that does not mean that we shouldn't ever do anything else. This is present in Christian music: my favorite band, Five Iron Frenzy, sometimes is rejected by Christian music stores because not enough of their songs are about Christ. However, none of their songs have any "sinful" material in them, and many address important issues in the world today. Does singing about things OTHER than Jesus make them bad? I don't believe so.
Sometimes, in order for a book/movie/videogame to express a view on life, some "innapropriate" material must be shown. For example, my High School recently put on a theater production entitled "Lie of the Mind," which dealt with domestic violence and dysfunctional families. Before the show, the Director commented (paraphrased) that "some of this material may be hard to watch, but it is an important social issue that must be addressed." How can we learn about problems in our society if we are not exposed to them? Consequently, how can we learn about (and therefore formulate opinions on) war unless someone shows us firsthand what it is like? Likewise, a movie about redemption has to first have a character who does things that need redeeming! Oftentimes, the understanding of good must be aided by the knowledge of evil.
The videogame series Metal Gear has many themes. Among these are genetic therapy, cloning, nuclear deterrence, censorship, betrayal, and truth among deception, but the major theme of the entire series, in my opinion, is the exploitation of soldiers in the modern world. The games describe how, in the past, warriors were viewed as heroes, lauded with praise and given apt rewards for their actions of keeping their country safe from harm. But now, in the modern age, soldiers are nameless, expendable tools, existing only to be used and abused by politicians and governments. How can Hideo Kojima express his views on this issue without giving the players a glimpse into this "controlled" warfare? That's why, in each game, the main character gets lied to, manipulated, and otherwise treated very badly by his government.
Another issue is that of violence, in and of itself. While I don't think that meaningless violence is godly at all, you must realize that people fight all the time in the Bible. God even helps people to win battles and whatnot. I'm sure God doesn't like war, but sometimes there's really no other choice. If you're surrounded by enemies on all sides, and they all want to kill you, don't try and tell me that you'd convert them! In fact, the Bible describes a supernatural "war" going on 24/7! In movies, books, and videogames, I don't see war as being "good" or "bad," but merely being a setting in which the story takes place, which can have "good" or "bad" things in it. The simple truth is, people fight. A lot. Therefore, the stories that we tell are going to be about fighting.
I'm not really sure how to end this little rant of mine (sorry for making it so long), so I guess I'll just repeat what I said earlier: in order to understand important situations, we must first have knowledge of those situations, and sometimes this requires seeing people do bad things.