Basically the title. The famous derp guns (like the Japanese heavies, the KV-2, the T49 and the Sheridan, ect.) have all been reduced to atoms because HE isn't a viable ammo choice anymore. When before, you could hit the front of a tank and do ~300-400 damage and do some module damage to make up for the long reload time, but now you're lucky if you do more than 150 damage frontally to someone and still have that same long-ass reload.
I know the argument of "oh, but durp gun bad cause no skill needed" is said a lot, but that's simply not true. To play effectively for your team, you need to stay alive to do the damage to tanks that other tanks couldn't. But now, if there's a hull-down tank and no way of flanking it, there's no point in engaging because they are impenetrable. This allows an actual camping mindset, and has ruined the game for me and many others.
Now, this would be a viable update IF IT ONLY APPLIED TO ARTILLARY. It makes sense to lessen the damage on tanks that can hit anyone from anywhere with no repercussions, since that's a sensible balancing act. But now, there's nothing in the game to help against Kranvagns, Chieftains, and the many Russian TDs and Heavy's.