Visual stimuli is a marketing technique, plain and simple. Those people who insist CoD/Battlefield are great games are weak-minded against the manipulation techniques that companies invest millions into getting right.
I don't want to sound like some conspitribal, but this is known fact. It's very easy to make money off of what looks close to reality. Our brain finds it very easy to identify, iconify and grok it, as opposed to something like a game with ASCII graphics.
Basically, people who play games "for the graphics" have brains which are very good at optimising and streamlining lives to the point that they have almost no challenge. They play the familiar because they either fear they won't understand, or cannot grasp the complex patterns that something like the old Point & Click games might.
