From the list of pieces that will be included in each national set, there are only 3 that are not used in A&A games – Commanders, Transport Planes and Trucks. I would hardly call that “half” of the pieces. The Half-tracks (representing mechanized infantry) and TAC bombers are included in the newest A&A games: Pacific 1940 and Europe 1940. Furthermore, I would point out that as the A&A games evolve, they have added new units so perhaps future A&A games will include Commanders, Transport Planes and/or Trucks. In Battle of the Bulge, they actually DO use trucks as well. Remember, the original A&A games didn’t have destroyers, cruisers or artillery.
Also, FMG is not making these pieces JUST for A&A. They can be used for many other WW2 games as well, some of which DO use the “extra” pieces.