When you create a follow-up hardware effort, you attempt to right the wrongs of the predecessor.
And this is exactly what Sony did with the PlayStation Vita. When asked how Vita would improve on the PSP's controls, Sony Worldwide Studios president Shuhei Yoshida talked about addressing any errors they may have made with their first portable effort.
"What we didn't do right with the PSP was where we started when we began the development of PlayStation Vita. We were very happy with having something very close to the PS2 experience in a portable format with the PSP, but we didn't do a good enough job creating the proper interface to really play games with graphics in 3D.
The lack of a right analog stick, for example. That's something we wanted to attack with the PS Vita because we wanted to enhance the portable core gaming experience and we have to do it right."
Another issue involved the fact that high-definition gaming came about soon after the PSP released, which immediately made the handheld's graphics appear more outdated. But Yoshida makes it clear that "pretty pictures" wouldn't have been enough, which is why they enhanced the user interface with the dual analog sticks, touch pad, and motion sensors.
With portable and mobile gaming rising with every passing day, Sony wanted to produce something cutting-edge…it's sort of what they do.