While you can pay your Maintenence Fees with a card, you have to do it all at once, in January. With the direct debit, it comes from your bank account once a month over a year's time, with no financing costs.
I had thought about paying maint fees with our Disney Visa to get the rewards, the benefit of interest-free financing of them over the year was a far better deal. We pay off our credit cards every month (much to the banks' chagrin, I'm sure) so we used our home mortgage as a cost of capital number, and the 1% reward could not measure up to the opportunity costs for that money over the course of the year, IMO.