I respectfully disagree. You’re committing a logical fallacy here ("the non sequitur"): taking the game’s one clearly fantastical element (zombies) and using it to dismiss realism everywhere else. In most other respects, the game makes a serious effort, arguably more than most games, to be as realistic as possible while still balancing gameplay and fun. One deliberately unrealistic premise (zombies) doesn’t make realism overall irrelevant to the rest of the game.