Balance is a funny thing in AH. Each GV has a niche and each fill that niche well. Which gv do most people take is they really want to be the cavalry and save a base at the last possible moment??? That is right, the M8 Greyhound. But, do you dare take them up against a tank in a 1v1? No way.
How often do we see the M4/75mm land kills? We dont, but when a town needs to be taken down which tank is usually the first chosen for that role? Yeap, the M4/75mm and not just for the Calliope version either, the fast reloading and hard hitting 75mm HE is only second best to the Tiger and T34/85mm in damage. But, factor in the reload rate and amount of ammo (not to mention the 4.5in rockets) and it easily will over-take in the Tiger and T34/85 in taking down a town.
Just how would a Panzer II or III factor into AH? Or the BT-7? The British Humbar or Diamler scout car? The M8 might have some competition in one of those mentioned, but everything else in AH would roll right over them. I see and hear your pain, but I bet more of the medium stuff (StuG III, Hetzer, Cromwell, etc) stuff is on the way.