QUOTE(warlordship @ Dec 17 2008, 11:31 PM)

I can see no reason to prevent people that have it already from continuing to play it, offline, without anyone else.
Um it's the same reason you weren't supposed to have it in the first place... whatever that reason may be. Maybe there is a contract in place, maybe there are laws that need to be addressed before US release, maybe they just don't want you to be playing it yet. Who knows, the point is just because you feel entitled to it and can't figure out why they don't want you to have it, that makes squat worth of difference.
Let's say MS has a deal with the publisher to promote the game in certain regions first and is offered a $1mill off the licensing fee of aquiring that game on the 360 for "Making their best effort to ensure the game is promoted in the manner desired and on the terms requested by the publisher".
So MS is sitting there and the publisher finds out that there is a loophole and demands MS close it. MS does so. Now the publisher says, you do everything you can to keep those who we didn't want playing this in the first place from playing it or we revoke your $1 mill bonuis for breach of contract. MS says ok, we do everything we can to prevent anyone outside Japan from playing it.
Again "I don't get it" sums you up perfectly. You don't.
Being limited to offline play is certainly not nearly as fun as having online as well as an option. But it's still playing it not in the region it was meant to be accessed. So if MS has an obligation or even just a desire to ensure that the game is only played in a certain region, that is your "why" right there.
Do you think cops go "Well it's illegal to buy pot, but that guy already bought it and we didn't catch him, so now that it's already in his pocket, we'll just forget about it"?
Stop thinking in a "how can I make this the best possible situation for me" way and start thinking about it in a logical and unbiased way and your "don't get it" problem will be solved.