I was thinking about this the other day when my friend was complaining about having to pay for Xbox LIVE, and I said you have to for most games. He replied that Blizzard games that use Battle.net don't. Guildwars doesn't either (yet World of Warcraft does) and it made me realize I don't know. So why is it that some MMOs (like WoW) will charge when others (like Guildwars) are free? Or Battle.net (free) and XBox LIVE (not free)?