SCEA does not develop games. That falls under SCE WWS.
In order for the Vita to gain market-share in North America, it would need games that appeal to children, who make up a much larger percentage of the hand-held consumer base than in Europe or Japan. They would need more IP that they could market across an array of media, including toys and cartoons. They have nothing like that.
My opinion is that Sony needs to invest in the creation of several such properties to see if any of them click. Honestly, you think they'd have a leg up in that regard thanks to their film presence. Another option would be to negotiate exclusive game rights to a toy/cartoon property owned by another company. They have the ability to turn that into a quality game series, not just a crappy one-off like you usually see.
Before someone says anything about that copying Pokemon and Nintendo, it absolutely is, but children don't give a rat's ass who copied what. They just want the next popular thing.
When it comes to creativity and artistic control, Sony's World Wide Studios is probably near the pinnacle. They allow their top developers to decide their next projects on their own. However, in certain regards, that's also their Achilles' heel. Nintendo's consolidated power structure allows them to manage their franchises extremely well and to leverage them into perennial money making machines. Sony's approach is fantastic for diversity but it makes pin-point marketing and direction much harder.
