Sorry, but in my opinion a monthly fee for any game, no matter how large is just out of the question. I happily pay yearly for Xbox Live, and all the services that come with that, but I won't pay every month to play one single game, especially when games like Guild Wars give you the exact same experience, for free.
And there's no reason why it can't have multiplayer, both the Xbox and Gamecube versions gave you split screen, okay, so on the PS2 that you'd only be able to have two people playing, but there's no reason why you can't, and just team up with others online.