Actually, the aaht was the focus of multiple nerfs if memory serves. Consecutive too. 1v1 players felt that when they played usf it was too easy for them to lock out their opponents. It was quite the offensive beast when it came out. The machine guns actually shot bullets instead of nerf darts. The main cannon actually hit infantry and would mess them up. I think the suppression applied like the mg42 as well, it had this large area of effect that could stop large blobs pretty quick.
it was sort of a buff and a nerf at the sametime. they made it slightly sluggish however it can fire 360deg angle arc unlike the locked 210 deg rear facing arc. The damage of the 40mm bofors was nerf too, which in my opinion is good thing.
The biggest change is the timing of it, the old AAHT could be out during the first 5min in 1v1 games which has a huge impact on early and mid game before any direct counters against it. Apparently Ostheer players dont like it, hence it was delayed behind tech requirements for a unit that dependent on early to mid game to shine. Note that OKW has the same amount bullshit AAHT early game, hence they were locked behind tech too.
USF at the current state, most player would just prefer M5stuart because it come out earlier and its less frustrating to micro at mid to late game