Keep in mind, that when people say "realism", they don't mean simulation. The military shooters are realistic in the sense that they don't take place in outer space against laser-toting aliens. "Realism" is very much a term that is used on a sliding scale, with something like Battlestar Galactica being "realistic" in a way that Star Trek wasn't.
I think a whole lot of the problem is that too many developers are actively trying to make their games more like Call Of Duty. Fighting Nazis in space, make it look and play as close to CoD as possible. Western franchise not burning up the sales charts, let's bring it to the modern day. And on and on.
I think Homefront is the game that really fell victim to the CoD fallacy. They've pretty much admitted that they put most of their resources into the MP side of the game, which is why the single player campaign is so short. This is yet another sad case of people not paying attention to history. You don't get to be a major player in the MP market unless you're company has proven that they can deliver the goods. How do you prove that... by delivering a damn good single player game.
Instead of trying to out-CoD the single player campaign of CoD4, they tried to out-CoD the MP... and, not surprisingly, most people didn't give a shit.