I don't understand your logics sir.
None of my CC has annual fees including my airlines credit card. I got free use of the money for a month, paid them off before interest charges, and got cash back or miles back. What is not to like?
There is NEVER free lunch. If you use their money for a month, then you have to give your lifetime purchase history.
I guess that your history may be more valuable than interest amount during the grace periods.

