I feel bad for Persona 4 Golden. It's such a highly reviewed game, yet it won't be marketed well at all. Funny thing is, Black Ops 2 Declassified on the Vita will probably outsell it. Maybe Vita needs to change its gameplan when it comes to games that are good.
In Japan, the 3DS has a lot more games than outside the country, and the 3DS just feels very portable and not consoley if you understand what I mean. Sounds odd, but that's how the 3DS feels, and who knows, maybe that image has also affected the perception of the brand in Japan.
In most part, it could also be because of the 3DS's initial presence in Japan. It got a headstart and somehow used that to its advantage despite the sluggish sales in the beginning. Vita also doesn't have that killer app, like Monster Hunter, or DQ, or Mario, or Pokemon, maybe the Vita can get some Final Fantasies that can help it out. It also has Persona series and Disgaea but they're not as strong compared to what the 3DS has.
The franchises that Sony are relying on now are Western IP, which doesn't perform especially well in Japan. Right now, I believe the major detriment to Vita's software sales mostly have to do with its install base. The 3DS has eight times that of the Vita, which could be throwing off potential developers from making a game on that platform.
Zero Escape: Virtue's Last Reward = best game ever made.
