Perhaps becuase it is terribly difficult game.
Setting the keyboard assignment can drive someone mad, this has made me unninstal ArmA and ArmA2 several times.
Tehre are so many mods that it required constant update and the system to do so it´s very complicated for non IT-skilled players.
The movement of the player in the game in first person is amazingly claustrophobic. It seems you aretrying to move a telephone box instead of a soldier.
If you go to multiplayer and do not have a squad just find people waiting for a chopper than never comes and shooting each other due to boredom.
Despite all of this i think it has to be a good game for those who know how to sort out all these problems.
I dream of the day i can sit down and play OPF, Arma, Arma 2 without problem, in the meantime i keep these games waiting on the shelf in my cave. Hopefully BI will work more on these aspects like making games more user friendly, etc.
AH, other thing. I could not find people who want to play from the point of view of insurgency. That would be great, just pure guerrilla fighting, just aks, rpks, rpgs, strellas, EFPs, IEDs,...etc, against more advanced civilizations ;)