They don't know they're dead. If you shoot them, sometimes they drop ammo boxes. Even as we spoke, a putrid zombie shambled into the room, then started leafing through my copy of Maxim magazine. And he's getting stank all over my magazine. When I was a kid, the only bad guys in video games were robots or communists.
Dead people are cool.
You know, I think zombies are misunderstood. So often we shoot them on sight, like we do dinosaurs. Never before has man put forth a true, scientific study of what exactly makes a dead person tick. He picked up a piece of furniture. Now, on the count of three, you grab his arms and I'll whack him on the head with this coffee table.