Some people just prefer to pay as they go and not use credit; no bills to pay later. A debit card is little different from paying cash, at least as they've always been to now.
I've had debit cards that have $500 daily limits - only to the bank's advantage. Putting in a PIN - only to the bank's advantage. Immediate debit from account - only to the bank's advantage. Less liability for fraudulent usage - only to the bank's advantage.
I just don't see where the my advantage would lie other than some "peace of mind" thing.