I have played Asherons Call I, City of Heroes, a zyrka 3d chat site and we were able to purchase game cards to do so.  I would rather purchase a game card for 25$ than use my visa card and I think there are a lot of young players who probably dont even have credit cards. But they may have access to the money to purchase a game card at Best Buy or Target.  This is the only game I have ever played which in which you cannot use game cards.