Also, an important note on the talk about graphic-options (In case it havent been mentioned yet). Being able to lower the games graphics too much quickly becomes a problem in PVP. Users playing on very low settings are able to spot other players a lot easier than they who have higher graphics enabled, obviously because of more clutter and vegetation covering their sight. This is something that all multiplayer-based games struggle to balance, especially big and open games like ArmA. This often leads to competitive players lowering their graphics just to be able to see eachother better, and care less about the actual immersion. And that's a game-breaker if you ask me.
I'd say this is also a problem in coop, as your comrades can spot enemies that you might not be able to see at all from that same position. I've experienced this as rather frustrating in the past, seeing parts of your group shooting like mad men through the bushes, while the rest have no idea of what the hell they're shooting at.
So I believe that lowering graphics has to have a certain limit for the game to be relatively fair, eventhough it's of course technically possible to have even lower settings available.