Very interesting topic, I think I'll trow my two cents in.

As many other have pointed out I don't think that realism and fun are mutually exclusive I think that one can have lots of fun while at the same time playing a realistic military simulation which is what ArmA is. In the past I think TG has done and continues to do a great job at balancing this. I don't believe that there is any reason for us to try and "play military".

Personally I feel that one of the best ways to do this is to make realistic missions that actively encourage teamwork. At the core teamwork is where almost all players derive fun from ArmA, if people just wanted to shoot stuff there are plenty of other games that are smoother, better looking and less frustrating. However the one thing that draws people to ArmA and sets it apart from other games is the necessity of strong tactically sound teamwork on a level unprecedented in other FPS games. Therefore I don't think that realism should be our primary focus, instead teamplay should be our primary focus.

That being said in order to promote teamwork realism is one of the best tools. There are very good reasons why the military is organized the way it is platoons->squads->fireteams. Making missions where it is essential for those elements to act in a coordinated manner established the framework around which solid teamplay can be built. The most effective way to do this is provide realistic scenarios, making missions which impose realistic limitations and objectives on the players makes teamwork essential for mission success. In addition these limitations and constraints will push the tactics employed to mirror those of real life. Again we see there is a good reason why the tactics used in real life are the ones that are used.

So in summary in no way should realism be imposed on the tactics and organization of players, there is no need for ranks or Sirs or any sort of pseudomilitary organization. Instead providing a framework of teamwork in a realistic setting creates a blend of realism, teamwork and comradely that is both satisfying and FUN for everyone.