Credit cards I don't get the problem

Credit cards have exorbitant interest rates ,we all know this so why use them and then bitch about the interest rate.
If you use them and don't pay them off buy the due date you pay interest .
We use a credit card for all purchases and pay off on the due date.
We pay $45 dollars yearly charge but get points and collect between 3 and 4 $100 gift cards each year so we pay no interest and make around $300 because we use a credit card wisely.
Am I the only person in Australia who is on to this?