The reason why it is good for global economy for Japanese Yen to depreciate is because Japanese's tendency not to spend but save. For countries like China and U.S.A. that likes and is doing the spending, their currency should appreciate. For countries like Japan and Taiwan, their citizens like to save, their currency should depreciate so their banks will invest their savings to foreign entities.(carry trade) Make sense. I hope so. This is best for them to depreciate their currency right now so global market will benefit. Opposite is the worse situation for money supplies worldwide.