This.
Because cosmetics don't matter.
They have no bearing on anything other than personal taste for a skin on something.
Just like the mounts in the shop, its utility is unrelated to anything other than personal taste.
This argument is so exhausting.
It's almost like hearing you people say "Well, I pay for a monthly gym membership, but they had the AUDACITY to charge me $20 for a tshirt! Can you believe it? I pay monthly, so I should just get tshirts for free simply for showing up and putting in my time!".
Maybe they have competitions or other such things where you can win prizes, but otherwise merch is merch.
Let's be glad Blizz stops at the "meaningless cosmetic stuff" and doesn't implement currencies, like being able to buy leggo or dom shard currencies.