I miss in the Arma series a tool for sharing information about enemy position and movment.
If there where implemented a basic message/repporting system it would be a new aspect to the game for using of recon and observation post missions.
Also it could be used to give objectives to units from a commander/platoon leader.
All units have the same mission, but a leader could chose better disposal of troops insted of all engage from same direction.
It should be like a message sent from unit to other relevant units chosen by sender.
In most modern military radio communication systems there is text message options.