Because we're their customers. They should change what they do to best serve us, just like any business.
But it ends up in a ridiculous situation.
As I said in my post above. I don't want my bank to block my direct debits, just so I can't go overdrawn.
Sure, it's good that I don't get fined by my bank in that instance.
But what if my payment (which they now blocked) results in an even higher penalty from whoever it was due to be paid to? How are the bank expected to decide when it is in my best interest to have a payment prevented?