PropheT wrote on Dec 18, 2014, 23:10:
"While we agree that this would be a good way for us to make more money, what we're mostly interested in is the money. We think we'll make a lot of it.
We look forward to ignoring any feedback you may have as we move to implement this feature."
That doesn't even really make sense. For every schmuck who buys extra game time off them to sell in-game, there's a person in-game buying their game time with gold instead of cash.
Blizzard would, in the long run, break even. Though surplus game time floating around in the market would buffer it a bit. But if there's too much game time and not enough buyers, then people will stop buying the game time, or the prices will plummet, etc.
Unless they charge significantly more for the time codes than for normal monthly subscription fees, they don't make much money, if any at all in the long run.