What you're really missing is that the Xbox is a non-presence in Japan.
What you're missing is
the Xbox isn't the only on-line enabled console this generation.
There are plenty of PS2 games that have some form of on-line play in Japan, but it always inevitably gets cut from the US release.
I attribute this to the seeming lack of enthusiasm for on-line console games in Japan, and the Japanese developers tendency to pick screwball on-line options like specialized Japanese only servers, or direct dial play.
Armored Core is a prime example of a game series that would benefit greatly from the retention of on-line play in the localization. Two AC games with on-line play of some form were released in Japan, and due to regional discrepancies had it removed. The Versus mode of the AC series is very deep and the lack of on-line play prevents most players from discovering the depth and having a good time playing against other people.
Then there are the Capcom and SNK titles with on-line play yanked from the PS2 versions.
There is no excuse for these games to continue to be released sans on-line play on the PS2.
I wasted some time doing research on the total number of PS2 on-line games, and the East versus West difference. The overwhelming majority of on-line PS2 titles released here are Western developed as well.
Japanese developers have got to start taking the global market into account when designing on-line games.
If they don't, they're going to lose ground to Western developers in the on-line market; and continue to alienate fans like myself who want their games, but will not pay for a castrated version.
I don't have much faith in Japan next generation either. A lot of pie-in-the-sky Playstation fans seem to believe the PS3 will suddenly allow Japanese developers to release on-line games.
Folks, the only thing that's changing next generation is the hardware that sits under your television.
You're still going to be using the same Internet Connection.