You forget that Japanese devs are pondering breaking into the western markets as they grow bigger. So there is a disparity in Japan; who cares? The big money is in NA and EU and that means multiplat even if a game sells like ass in Japan on 360.
Japan is such a miniscule part of the big picture anymore. It doesn't really make sense to give that region as much weight as we did in the last generations. Their games are mostly a dying breed. Save for just a few benchmark titles, game making really is a dying and antiquated art over there. I would go so far as to say they are becoming game makers for a very niche market because they refuse to adapt to a changing market.
MS has arguably shown better advances in Japan this generation than the other 2 established brands. It wouldn't make sense for them to pull out now.
"Man is born free but is everywhere in chains" - Rousseau
