There are those who decry the very existence of credit cards as they tempt people to spend money that they don't actually have. I have to admit that I'm not amongst that number. Credit cards actually allow people to smooth their consumption which is, in this world of variable incomes, an extremely valuable option for them.
It's also true that with the competition to actually hand out the cards the canny can borrow money without actually paying any interest: there are the 0% credit cards for example. It's also very easy to move money owed from one that is charging interest to one that is not, the so called 0% balance transfers. These options, plus the fact that if you pay off what is owed on time you pay nothing at all for the use of the money, either in fees or interest, makes me think that credit cards are a great idea.
In fact, the way in which even the poor are now able to get credit cards strikes me as being an improvement, not a problem. For, after all, it's the poor who need the most help in smoothing their consumption, isn't it?