#2a) Trying to lose the stigma of "gambling causing people to not only lose all their hard-earned money but run up a load of debt as well..."
#3) With Credit Card, the casino pays a percentage for the transaction, the other way is at worst "even money" for them, as the company that's doing the transaction handling is charging the customer...and it wouldn't be surprising to see the casino's either holding share or getting kick-backs...