Pro : It's could to kill the private 3rd party market for gold and hopefully discourage botting eventually. Making $0.25 an hours vs. $2.50 is a huge hit to gold farming botters. A 90% paycut is enough to make most people quit their job. :)
Botters don't sell gold, that's the point, they sell gems. This is why gems are so cheap. It is the genuine player that sell gold : it take a very long time but it is balanced by the profit.
Botters are now gonna flood infinite cheap gold.