You need to be aware that MP lag in arma now depends on how the mission is build. Not the game itself. If its a bad mission with a bad server and alot of scripts running with invisible script errors all the time, the server can lag alot, but it has decreased dramaticly over the years. (Domination or MSO as the most common ones and also that retarded gamemode "dayz") These missions really stretch and pushes the old arma 2 engine to its limits now. Hope arma 3 gets a touch better on that.
Anyhow, I think ED needs to keep focusing on the flight and strategy part of DCS and the CA module and continously improve them instead. (Nevada map, future maps, future airplanes and so on). I would rather have a JTAC/FLIGHT/STRATEGY game that is super realistic and high functioning in those parts with alot of gameplay than a game that does it all in a "semi-blah" way like arma and most other games does today. If their resources goes to making infantry parts and what not like suggested here in this thread, they simply wouldnt have as much time/money/manpower to put into the detail DCS is know for right now.
Detail equals time.
//Mug. - Arma and DCS player.