Damage, AA is pretty bad overall, Core Air can kill any unit and any army comp and bases while AA is incredibly limited, no other counter unit is as limited as AA which makes them a chore to build as they provide no benefit against a ground army ( even cyclops can damage infantry for example while AA does almost no damage in the case of Wolves )
Unit Attack Type, Another issue is that Core Air can attack in all directions, even while running away. This alone isn't an issue since Wolves and Reavers also can, but considering you aren't going to be making very many AA ( because previous and next points ) , this leaves you with the next best AA which is Marines and Grunts. However these units are unable to attack while not facing towards their enemy ( and slightly to the sides ) meaning if you are forced into a retreat Core Air will completely shut you down with nothing to counterplay against.
Leader Powers, Yet another issue is leader powers, ground based units are simply too easy to nuke while Core Air can easily split or fly past a telegraphed power while Marines and AA get shredded into nothingness. This is a pretty bad issue against Wolves especially since they have no escape ability and cost a fortune in power.
Scalability, Core Air simply scales better at T3. Core Air gets very strong upgrades at T3 ( keep in mind these upgrades are essentially free since core air requires no power ) while Marines, Grunts and AA have no T3 upgrade to keep them relevant, this issue also compounds the first.
Economy of scale, it is true that core air is very expensive in terms of supplies but this is missing the point, Supply pads never increase in cost and air doesn't cost power. This means Air can be double or triple pumped with no issues ( since the player will just build nothing but cheap supply pads ) and meanwhile using spare power to get the T3 upgrade, meanwhile AA takes a very large chunk of power to build which halts progress towards T3 and other upgrades/units/powers ( and Marines can't shoot in all directions so they aren't a very good solution long term ).
ROF, Core Air has a very fast ROF while AA is very slow, this means Core Air can instantly switch targets and begin dealing damage while AA tends to miss targets or overshoot and takes time to switch targets, this compounds the other issues to make AA very difficult to use in real gameplay.
Unit Counter Type, Air has no AA unit type. This is an issue as air mobility keeps them away from ground counters and ontop of that Air counters vehicles ( which AA is a part of! ) so Core Air....Counters AA..? combine this issue with the first ( Air nukes all unit types pretty evenly ) and this makes AA really hard to justify in an army comp when they get shut down by the units they are supposed to counter.
Closing Remarks, I expect a response being in relation to the tests preformed but I discredit those tests for 1 reason: HW2 is not a simple units smashing into units game, it has leader powers and economy and passives. So while AA WILL win in a test of even numbers or situations where full pop armies attack each other with no interference, the actual game itself is not even remotely close to this. If you tried to smash your full pop of Wolves into a full pop of Hornets, you would just get Mac Blasted and lose ( or glassed against Banished ) while any leader power you throw out more than likely will be dodged will little damage taken ( and even if you win, they will just rebuild faster than you and start the whole process over again, only with your powers on cooldown... ) My proposed solution would just be giving AA proper damage against ground armies, a T3 upgrade and AOE, This would not make Air useless because economy matters and would make sure Air spam has a proper counter ( rather than just being an instant gameover ).