The thing with Premium ammo is the more Premium ammo people use, the more credits they will need to pau, and the greater the need for Premium tanks and Premium time will be. That's how credit-bought Premium shells end up making WG money.
But Premium ammo has been in the game for a long time, and is already an integral part of the gameplay. It turns out using premium ammo does give a tangible advantage over time, and since it's already in the game and has affected the way tank are balanced, the chosen solution is to make it more accessible to players. That's the theory, anyway. But are the changes necessary? Well, many WoT players are asking for precisely these kinds of changes with regards to Premium ammo, and WGs own data does show regular use of Premium shells increases your damage output. So yes, you could argue they are, in a way, necessary.
APCR already has less normalisation than AP, but I can't agree they should have less penetration? That's not how they work; since the projectile is smaller and faster, they do actually penetrate deeper. Thats the whole point. It makes way more sense that APCR make less damage but flies faster and penetrates deeper.
Also:
I agree 1 T7 and 6 T8s is frustrating.