Last time the biggest issue with the withdrawal system was the lack of TF2 keys, but that's all fixed, now there's enough TF2 keys for everyone!
Unfortunately changing the deposit ratio to 1 had one serious consequence, most people aren't willing deposit their cs:go keys on dispenser, which means they can't buy any games without converting their keys to TF2 keys. You can already see this as the lack of buyers on the most popular titles.
Current withdrawal rates for CS:GO are quite fair at the moment, so there aren't any huge disadvantages for sellers to withdraw their credits as CS:GO keys.
The quickest fix would be bring back different deposit rates for CS:GO keys that should certainly increase the amount of sales, and it would also increase the amount of collected fees.