The gold you get from selling a token doesn’t Come from blizzard but players, thus you can’t just say “i’ll take 1/2 token for 100k gold” since the tokens are auction by player who paid for it with real money.
What you’re asking for is no different than asking blizzard to print money & fk up the economy
The shop is not part of the actual game. There’s no (virtual) physical place you need to visit with your character and talk to an NPC there to buy stuff. That’s why.