Pay per view charges aren't set by a cable company though; they're set by the manufacturer of a separate product (Ooh let's say a WWE show for example) because that's how they generate revenue.
Blizzard isn't regularly a platform for other services now, is it? Your point would make sense if other artists were creating items for sale through the store; they're not though.
You pay them a sub, which has traditionally allowed you access to anything/everything they develop in-house
(TCG actually does match your point btw; it's a tie-in product created by *another* company who charges you for it, and a perk is provided in-game, but Blizzard themselves don't directly take money from you for the item). During Wrath they started allowing mounts to creep on, then pets for charity, then pets purely for profit and now we have them claiming "oh this art is too much work" and "oh that art is coming along, but limited artists and such you know
" then you have shit like this coming out, off the back of an absolutely abysmal tier preview for T16 (don't even dare try telling me a single one of those sets even matches their respective class).
The analogy stands, you just assumed "the cable company" is who sets PPV charges. They aren't.