I'm guessing that it more has to do with the state of their 3D tech. Maintaining the "sweet spot", and all would be pretty difficult with a handheld controller

I'm guessing that it more has to do with the state of their 3D tech. Maintaining the "sweet spot", and all would be pretty difficult with a handheld controller piloting a console. Have you watched kids (or maybe even yourself) play a game? Writhing around in your seat, leaning with your virtual character's movements, leaning forward at those particularly tense moments... it all makes for a tough sell when you need to view your 3D screen at a particular angle in order to see anything but a blurry mess.