There is so much wrong in this statement that it's absolutely hilarious.

1. UPad vs. Vita. The Vita is obviously the better handheld because the UPad is not one. But the UPad just is the superior CONSOLE CONTROLLER. Clickable analog sticks, 4 shoulderbuttons, bigger buttons and better ergonomics.

2. To achieve even half of what the UPad does, Sony needs to work around a lot of limitations. First of all there is the inferior transmission method Sony uses vs the custom protocoll from Nintendo. It's fine for simple stuff like maps and inventory but streaming games on the Vita is a lagfest. Tried to play a PS1 game with remote play and it's just not fun. To achieve some more complex stuff on the Vita the handheld needs to run it's own "game" so that the PS3 only needs to send data packages about the state of the game and not full pictures. Also, I can not imagine how Sony would solve a game like Takamarus Ninja Castle with that sort of input lag or that Golf game, where you need that IR sensor bar on the pad. There's just a lot where Sony or the developer needs to be fricken creative to emulate what the Wii U does out of the box.
The Vita does obviously other stuff the pad doesn't like being it's own standalone handheld, what it was created for.

3. The install base is just not there for this kind of investment. I read somewhere that it would make more sense to develope games that are exclusively controlled with the Wii balance board than the PS Vita.

4. Even if the install base is big enough, the Vita is still an optional device to the PS3 while the UPad is mandatory. Look at the GC+GBA situation. Crossplay functionality was potentially there and the install base was much bigger and there were still only 3 games that supported it. Look at move, look at Kinect, look at the motion plus controller, if it's optional, third parties won't give a shit.

5. 300$ vs 500$. And 500$ is being generous, you would need a memory card and a HDMI cable to get the PS combination running on the same level the Wii U is.

6. Convenience. Boot up the Wii U and everything is ready to go. In the other sitaution you have to boot up both consoles individually, register the Vita with your PS3 (once), start the remote play program on both devices and so on. I haven't done this in a long ass time but I remember enough to know that it's not even remotely as convenient as the Wii U situation.

So in short, you would pay much more to get an inferior experience, IF a lot of developers would even care, which they will most probably not.

I have both a PS3 and a Vita.  Sadly, the vita's been sitting on my desk in it's "Official" cradle for over a month now without being touched.  I have the 3G model and have had it listed on Craig's List with the 8GB card, cradle, box and everthing for $180 and no one seems to have any interest.  It's a good system with too few good games.