You're missing the fact that in original ArmA2 you also wonder around and no nothing else than shoot random people. What makes DayZ fun is the teamwork, just like in original ArmA2. You find some people on skype who play the game, and team up with them, killing other players, or just bandits. The worst thing is when a hacker comes into a server. In fact, if there are at least 30 players, there is 99% possibility that there is at least one hacker who will try to make your gameplay less exciting than ever.