Sigh.
Blizz is already making tremendous profit off of WoW. They could literally already offer Vanilla servers today and still be wildly profitable. It literally doesn't have anything to do with money.
WoW is a cash cow. The whole point of a cash cow is to spend the minimal amount of money to keep the customers happy enough while raking in the profits and using those funds for something else.
Blizz is already making $20 / mo on some subscriptions by virtue of the tokens. It doesn't matter who is paying the money, what matters is that for everyone who buys tokens, Blizz got $20 for that month's subscription. In return, the amount of content is only a bit more than WoD...about on par with MoP in some regards, and massively far behind from what was offered in either BC or Wrath.
I have no interest in encouraging a large corporation to increase their profits even more by offering a minor concession. It would be like paying an extra $10 for a $2 addition. It would be stupid on my part, but I'm sure Blizz would absolutely love the idea.