Just because you don't pay doesn't mean you get an inferior service. Steam has most everything you'd need directly involving gaming, while xbox live has more multimedia features and a more streamlined setup. The fact that it's free, there's free user created content, and dedicated servers make it a great service.
Remember that Microsoft tried the Pay model with Games for Windows live. Granted it was a pretty much just a hollow shell of Xbox Live, the complete rejection of a pay to play model for regular (non-mmo) games is still interesting.
PSN has some issues compared to Live, especially related to the social/communication aspect. Short of making XBL Gold free, Microsoft could still make all their features (crossgame voicechat, crossgame invites, netflix, whatever) a paid service but online multiplayer free. I just don't see a good reason why microsoft has to charge someone to use their own internet connection to connect to another user when both users have paid for their games.
Demon's Souls Official Thread | Currently playing: Left 4 Dead 2, LittleBigPlanet 2, Magicka
