With the benefits and bonusses that creditcards give in the US I can see the sense of using them. Consumer protection is a good one. I must add that there are a bundle of laws and regulations where I live to handle that sort of thing, but it can be a bit trickier to get money back after having used a debitcard...I think.
And as for the risk to loan money to someone who didn't loan before; I guess it just depends on how you look at it. If someone applies for a loan, has a good job and income, a car, pays rent, and has no history of trouble paying back anything, you can generally assume that the person knows how to handle his/her money. A good conversation about the person's money managing will likely reveal any other problems. When a person had failed to pay back something in the past, there is actually an institution which keeps track of all that. Mortgage interest rates do not differ based on 'credit score'. But the amount that someone is allowed to loan can differ based on the perceived credit. And when people have trouble paying off their mortgage because their income actually did not support it, their advisor can also expect a visit & check.