Nintendo, Sony, and Microsoft all have their separate attitudes on online game play. Frankly I don't think anyone has really nailed it yet, but that is not a big problem. That is like arguing how the ARPANET/internet should be used in 1974. I really like Nintendo, but this argument seems really short sighted.
Nintendo is devoted to the single player/group offline play model. I do think that way is the best way to play games- and has always been.
Microsoft is taking what the PC game players have been doing for years, and crafting a version that works on the console. It is a lot of fun, but I can't say I am sold on the idea of sitting at home alone, and playing against some strangers. I really only use it to play with people I know, and I think that is the norm. But this is the direct and literal form of online play, in that you are playing co-op or head to head over the net.
Sony seems to be taking a wait and see approach, which as market leader is their luxury. Since Japanese players are not so much into the Half-Life type of online play, I can understand why Sony is rather lukewarm on the whole idea.
But in the end, the online component of consoles is going to be a lot broader and more subtle then what we have seen so far. You could have living games that continue all the time, and are accessible from your PC, cellphone, or even GameboyDS during the day- It would still be a single player experience, but online would allow a variety of 'controllers' to dip into the game during the day. Bungie has been hinting that Halo2 will have more meta-online interactivity- I will be curious to see what they have in store.
Or, just the notion of downloadable content should be thought through deeper. Now it just means new vehicles and maps, but the developer stops doing that once they can safely consider enough 'extra value' delivered. But what about episodic games? A game that offers a story that continues over a 'season' with weekly or month updates? Or just even smaller more discreet data, like a version of Animal Crossing where the weather for each day is pulled from actual realtime weather sites? Or a GTA game where actual news or CNN screen shots appear on TVs in the game? I don't know if that makes for a better game, but it is an interesting way of using the technology.
One of my favorite gamin experiences was Morrowind, which was a massive single player RPG. The designers felt that while the game was similar in many ways to online rpgs like Dark Age of Camelot, having other real players running around with names like "Sir Loin of Beef" would push the player out of the world. They are right, that most people online are Jerks, but Morrowind can be a lonely experience. I wished at the time that there was a limited sort of online play, so that I could interact with a few of my friends. So maybe the answer would be a mini-mmorpg where a small group of people could share a fully realized online world like Morrowind.
I hope Nintendo eventually gets the idea that online can mean as much or as little as a designer wants, and gives game developers the tools to experiment. There are too many developers farming the same patch of online turf.