Normally, a consumer has a debit card linked to his or her checking account -- a third party can handle payments processing, "decoupling" the debit card from the corresponding bank account.
If a payment is due to go out on a particular day, quicker payments processing means it's worth making sure there is enough money in your account the night before.
Also, for the last step - revenue generation- consider banks generating revenues through offering payments processing as a (white-labeled) service to other banks- wouldn't that also be revenue generation?
Mobile wallets and the increased importance of card security to reduce fraud are some of the major trends that are shaping the future of payments processing.