The middle east has seen a plethora of varying arms and armament. And I always wondered why the devs of the last insurgency never added any new firearms through out the games life span. Now with this new setting it would be a disservice to the community to not add new firearms. Personally i think some should be added with every patch. Now I am no developer but I can't see it being that difficult adding new ones every once and awhile. Anything ranging from old WW2 era rifles/MGs, to newer variants like the MG3, Mk48, RPK, M240. I find I have a low attention span and change my guns atleast 2-3 times a match so this is entirely self serving to me haha. But the MG3 would be a fucking wicked addition.
The difficulty with adding scores of weapons is less about the time needed to model and code them and more about making sure the game stays balanced. Particularly in a multiplayer shooter where players are on both sides, keeping weapons balanced between teams and with the other weapons takes a lot of thought and work.