I guess they decided to fund energy weapon research over ballistic missilesthen again, both sides probably have a ludicrously small amount of capable mobile anti-air batteries
because they decided that it was better to go make a ton of advanced aircraft instead, the thread is [obviously] more centered on fighter craft than any other type of vehicle. It doesn't hurt to have AA batteries that shoot missiles at you every once in a while, but the entire thread isn't about SAMs. In a sense, I guess they serve a minor role overall, like attack helicopters or tanks, you don't have to worry about those shooting you down too much because there's also another guy flying a jet that can take you on just as easily. Of course, I don't believe that they would leave all of the work to their fighter squadrons to pick off aircraft out of the sky, but that's the role that the fighter aircraft serve in this thread, shooting down other aircraft so the ground forces don't have to worry about resupplying their anti-air guys as often. In a place where just deploying allied aircraft is not economical, I can understand why they'd have AA everywhere, but they probably won't deploy AA loosely on the front, mainly because they can fit an tank in that transport aircraft in the same place as that mobile AA. Where they can deploy fighter aircraft, they will deploy fighter aircraft, you can't expect a unit that's basically entirely based on anti-air duties to survive against a bunch of guys with anti-tank weapons, that's why I wouldn't expect them to be deployed in large numbers, because it's more economical to ship a truck that can carry twenty fully-equipped infantrymen and a few MANPADs than it is to ship a truck that only shoots down planes.
Ace Combat also did an elite anti-air unit too, these guys do have a role but it's relatively minor in comparison to the ace squadrons that you have to fight against.