Most Indians don't want credit cards because they don't want to fall prey to them. Those who have them use them only when it's absolutely necessary. They buy what they need and pay by cash. Credit cards are addictive.
More to your point, there are many in the cities who have credit cards and use them often because they're convenient. Carrying cash or using debit cards when more people are moving to credit cards is foolish and a way to subsidize the people using credit cards.
I have credit cards that I use wisely. Always pay fully on time (no interest), make the most of the credit period by timing purchases as much as possible, etc. I don't have to worry about carrying lots of cash and getting change (or worse, rounding things up while paying). Taking advantage of marketing related discount offers from credit card providers is also another positive. Overall, credit cards provide a lot of value for me, although the social benefit could be argued one way or the other.