The tipping culture really has gone crazy in America! You are under no obligation to tip the maid... ever!! Maid service is one of the requirements of being a hotel. Now if you choose to do so, that's fine - I've done it occasionally when the cleaning service has been particularly good - but is it truly your obligation to make up for the fact that the maid is poorly paid by leaving him or her a tip when he/she's not even serviced your room?

Rant aside... MAGC works for the hotels because they spend less money on laundry and, yes, on staff - not because they altruistically want their maids to have less work to do. That's why you get the points or money to spend on food. So if you're concerned about the maids, then actually decline MAGC so that they get paid, and tip them on top if you choose.