i have fired a number of guns, when you are familiar with a gun and the way it shoots firing from the "hip" does not make it any less accurate. if your pointing at a target and fire at it the bullet will hit it simple as that
I'm not really a (real) gun person myself, although I have fired one or two. However, I have played some airsoft, and that was my experience as well. If you know how your gun aims and shoots, you can easily send your bullets/pellets where you want them to go without sighting in. In many situations it actually makes more sense than using the iron sights. If you've got the time, sure, line up a good shot. But once the shooting really starts you might actually be better off
not using the sights.
I also agree with the OP; the core misconception is with the term itself...hip firing. When you 'hip fire' in a video game you're not actually firing from the hip. As others have said, the 'realistic' system in games like CoD is anything but. In real life you (assuming you've had the training that your character has supposedly had in those games) could consistently hit a target that's standing still out in the open at forty feet without needing to use the sights. In CoD not using the sights would be a risky gamble. People have just gotten used to that system, and expect other games to conform to those rules.