I can think of at least two other reasons for getting a credit card: not wanting to deal with cash, and for situations in which using cash simply isn't feasible - e.g., ordering from Amazon.
Yes, yes, debit cards. I have a debit card, as it happens; I use it for buying groceries and ATM withdrawals. However, the bank which issued it has imposed a restriction: if I use it more than, I think, six times in one month, they will charge me a certain amount (I don't recall how much) for each excess use. I don't know how common this is, but it would certainly put a crimp in their use as opposed to credit cards.
And I still suspect Hannelore isn't fond of handling (filthy) money.