Why do you think that CAS should be literally unusable because your enemy made 1 AA unit? Plane crashes being dumb is one thing, thinking that a AA HT should negate an entire commander is well, stupid.
And why it should not? I go for pure Air doctrine so pure AA unit should counter my abilities so if I want use them I need to destroy AA unit or use planes out of the range.
Right now AA unit is not helping to prevent planes. It helps your enemy to make planes even more deadly.
CAS best ability is fuel->muni and AA has nothing to do with it.
CAS on the other hand negates any howizters. No enitre commander but howizters.
AA does not negate all commader. You still have conversion and Stuka dive bomb.