This is true, (and I dont belive any waffen doc has an AA halftrack, though luft can build emplacments.) but then again, the ostwind is very tough for an AA vehicle, and can actually repel heavy assault infantry without getting destroyed in one bazooka hit.
As for waffen in general: don’t pick your doc right away. If you feel the need, call in the light halftrack, then pick the panzer doc. That and your base has 3-4 AA emplacements. If your opponent calls in a plane, it will get shot down. Just retreat your units when you hear the audio cue, and watch the strike miss. (also, not all planes can be shot down. the arado for panzer division and the B-26 for US airborne fly too high.)
This, on top of the fact that if your opponent call is planes before late game, he is a bleeding idiot, or an AI, b/c you lose valuable troops you need to unlock with those command points.