I think they mainly need the Credit Card info to validate user accounts. Besides, it has been this way all the time, starting way back with Ultima Online and Everquest. Every single subscription based MMO was asking for this kind of info before letting you play, even if you had bonus time on hand. No big deal, as several other already pointed out: You can enter the info, then cancel the subcription right away if you want to and contine playing until your free month is up. If at any point you feel like continuing, just renew the subcription.