I disagree with that sentiment: I think that, in fact, there are only two things that can be unethical about the creation (not the distribution, just the creation) of fiction: plagiarism, and limiting the scope for the sake of ethical concerns.
All stories gain ntheir power through symbolism. Without that it's just a dry (if entertainingly written) list of events with no real relevance to anything. Add symbols to a story and the story becomes better. Better still if the symbols make any damn sense. A story has the potential to be extremely powerful if the symbols are taken directly from things that the reader is already familiar with - which means real countries, real technologies. And this is a good thing. You can bet your ass that most people react more strongly to "The United States of America" than to "Gondor." A good writer knows how to take advantage of this fact, when appropriate.
Realistic fiction is, more to the point, an effective means whereby the people can explore the issues of the day (or of the past), come to terms with them, and become familiar with the arguments and implications of any given position. Just because it's not read in a classroom doesn't make it any less valuable. Ideas presented in an intellectual sphere are solemn, severe, intimidating ideas; expressing them through fiction makes the ideas light, and it makes them easier to swallow (and I say, the world is tough enough to follow that it's plain cruel to not let people have their oversimplifications, entertaining trivializations, their catharsis and their straw men). The only real difference between this and any number of hypothetical suppositions made constantly in political and historical spheres is that in these fictions, more often than not, you get a fully developed character and a complete narrative in them. Which, really, makes them less politically driven than your average textbook. A textbook is based on the idea - and make no mistake, this is an idea that is politically relevant and even politically charged - that knowledge should be increased. A novel is not based on this idea. Maybe it advocates something else - but unlike a textbook, it is fiction.
All fiction takes place in the real world, with just a few changes made to it. In fantasy, there are lots of changes. In a military thriller, there's almost none at all. Some differences that a Clancy novel make are inventing the characters and the situations. All fiction - simply by choosing which parts to omit or which parts to leave in - makes a statement about the world. All fiction fictionalizes the real world. Where do you draw the line for what level of abstraction is "ethical" and does not excessively trivialize real issues? And for that matter, what makes it so wrong to trivialize the real world in the first place? Because it would cause controversy? Well, how many people have to be offended before it's called a controversy? I guarantee that at some point in human development there existed, or will exist, an entire nation that could be driven to outrage by, say, Star Trek or Super Mario Bros. In my opinion we should embrace writers bold enough to make an overt statement, rather than hiding them beneath layers of symbolism.
I'm not going to tell you not to read/play/watch them if they bother you that much, because that's not what you're talking about. I am going to remind you that reading fiction does not imply identifying with its message or protagonist. I am also going to tell you that it's plain absurd to expect all fiction to be fantastic.