Have a couple of suggestions.

First, how about being able to crush Runes for Precious Dust along with Gems?

Second, has Plarium thought about talking to Microsoft about being able to use peoples Microsoft accounts to pay for things in the Bank/Store? I do the Microsoft Rewards thing everyday and have bought many games/movies etc with them. You can cash in rewards points for cash to spend in their store. Maybe a card and/or just using their account to pay. Might be worth a shot.