If you're not using a card, they aren't making any money. Remember, they get a fee from every business transaction. You don't pay less for product with cash so why not use your card and pay off when you have a statement arrive? And no, I wouldn't pay it immediately, let the statement arrive.
If you're not using your card, you are a risk to them if someone hacks your account and they have a loss on top of the loss from your non-use.