Vita's going to have a hard time in Japan until Sony somehow mans up and shows that it's a reliable product. Sure, the failure rate's probably not nearly as bad as what the internet might make it seem, but there's still an alarming number of people complaining about it on the web, and you also have quite a few notable people -- Mihara from Arika, Takahashi meijin, several authors and voice actors -- mentioning they had or are having problems as well, which adds to the credibility of more anonymous failure reports. Once there's a few games I want for the system I'll have no problems buying it here in the states since Wallyworld/Target would have 0 problems with returns/exchanges within 3 months, over in Japan things don't go nearly as smooth, and it's not surprising that a lot of people are giving it a wait-and-see for the time being.
It wasn't the only thing that killed it but 360 in Japan never really got up from the RRoD fiasco, and if cards are played in all the wrong ways a similar situation could occur here as well.