Accepting payment via direct deposit to your bank is probably the most difficult method as it presents all sort of issues we would need to address inside of the software.
Issues that would need to be addressed in one form or another:
1. When you are on your cart page with all the order information on it, where do we send that information to when they press submit on their order? We would need to build an e-mail mechanism into the software for order information to be sent. It is not just as simple adding your e-mail address to a box in the software.
2. Since there is no logging of any personal information due to PCI Compliance rules, what would happen if you did not receive the order details?
3. There is no invoicing system, so the consumer would not receive any invoice for what they purchased.
4. If issue #1 and #2 failed the order could be lost in limbo and you would have received money with no way to track it back.
For all of these reasons, this is is why we rely on using a payment gateway because it eliminates each of these issues. I am sure we could code our software to make it work, but I am not sure we really want to at this point.
My personal take on using this method for payment is up there with sending my bank information to a Saudi Prince for a 500 million reward.
Also, there is also no buyer protection. If I send you funds this way and you do not send me what I paid for, I have no recourse. If I paid with a credit card, I always have a way of disputing a charge.