First, Sakurai decided that he wanted to make a shooting game for Nintendo's new handheld, which he knew would be more powerful than the DS. Then, according to Sakurai, "Mr. Iwata said, 'Maybe you might like to do some Nintendo franchise,' and I felt that if the match was good, then there's definitely room for that." Sakurai was thinking Star Fox, but "the game design incorporates a lot of different views; for example, flying and shooting sideways, or turning around and shooting behind -- and I felt that there were some restrictions with Star Fox in this regard." (Of course, Star Fox ended up on 3DS anyway.)
It was only after coming up with the game concept that Sakurai learned of the 3D screen, and "quite by chance or luck, [Nintendo] found that to be a very good match with the gameplay idea."
Sakurai also proved that he's basically as clueless as the rest of us about the renewed popularity of Pit, the protagonist of an inscrutable NES game about shooting mice, collecting hammers and being turned into an eggplant. "I think -- and you can recognize this from the original game, too -- that he has sort of this carefree, worry-free sort of air about him, and that, I think, provides a positive outlook for the player and relieves some of the stress that you get from more serious games."