I know this is going to sound a little crazy but i also think Vita is a little underpowered. Obviously that's not really Sony's fault since Vita was pretty top notch for mobile hardware when it was announced. But the fact is that PSP was much closer to PS2 than Vita is to PS3 power wise. Obviously PS3's cracy Cell cpu doesn't help either. This results in last gen games being less easily ported to Vita. One of the exceptions obviously are the Rayman games, but those run at 1080P/60fps on PS3 so there was more room to downgrade.
Most important thing though would be the fact that if Vita was more on par with a PS3 and more similair in architecture, they could have made you're digitaly PS3 library playable on the go. And a handheld that would have made that possible would have sold very well.
But who knows maybe we will see a handheld version of the PS4 someday, the hardware is more suitable for it.
