Okay, first up I am not talking about pure FPS games or multiplayer games hosted by one of the client (a la Dungeon Siege) - this is purely about "persistent world" games such as Ultima Online, Star Wars Galaxies, City of Heroes, etc.
With MMO(RP)Gs, there is a cost for ongoing development, maintenance, upgrade and running costs of the server farms to host the games, so should it be reasonable to charge users of the service a monthly fee?
I'm not going to poll on what people think is a reasonable subscription charge, but I'm interested to get an idea of what people expect as a payment model.
Subscription charges are invariably prepaid and non-refundable, some current models give you a discount if you sign up for 3,6 or 12 months too.
While it's not something I've come across yet, I wonder if people would be more inclined to pay if they knew it was for time they actually use, rather than per calendar month too.
To give you an idea, City of Heroes is $50 to buy (same cost if you download it but don't get the media or manuals), and $15 per month to play - Star Wars Galaxies is the same but there is no download option.