The Vita is getting a large software rush in Japan starting at the end of the month, so they decided to drop the price because they felt this is the time it would boost most sales. When there are plenty of new games.
There isn't a large amount of software being released right now outside Japan so it's likely they are saving up the announcement for a later time, possibly even E3 since Sony touted the Vita as the "companion device" to the PS4. Besides, the international release of Vita was two months later than in Japan.








