What about all the free money you're leaving off the table in miles and cash back? I've had a credit card for about 3 years, and while it isn't much, I've never paid a dime in interest and I'm up roughly $800.
That said, I do get annual cashback of 1% on one of my cards.
I've have some credit card debt, none of it carries any interest. When I buy appliances or furniture I usually take the interest free financing despite having the ability to pay. Why pay a few grand today when you can spread that out interest free for 2 years and let that value appreciate? I would have lost out on tons of money if I had sold investments up front to buy those goods. So instead of getting rid of all that money a year ago, I got 30% gains in the market.