The company's president is waiting for the adoption rate of 3D televisions to go up.
Nintendo President Satoru Iwata addressed his thoughts on 3D console gaming in an interview in today's Nihon Keizai Shimbun.
When asked if the Wii would be made 3D compatible, he responded that it really isn't possible with Wii hardware. "If you display a 3D image, the image quality becomes extremely bad, so we'd probably do it with the next system. We're thinking that the timing should be once the 3D television adoption rate crosses the 30% mark. We're looking at the adoption trends."

The newspaper asked if the 3DS represented Nintendo riding the wave of the 3D boom that seems to have invaded video gaming as of late. Iwata was quick to point out that Nintendo is not new to 3D, and that they had already been experimenting with immersive 3D gameplay fifteen years ago with their Virtual Boy system. Admitting that the technology "was not ready" at that time, he stated that his company put 3D gaming on the back burner until approximately two years ago, when they realized that they finally had the technology to create "a satisfying product".
Iwata said that the goal of implementing 3D is to give players the ability to sense their position in a game more easily. "In a game where the stages extend into the screen, it's surprisingly easier to control [compared to non-3D]. This is functionality for making games more pleasant to play, not just for show," he explained.
He was also bullish on the future of 3D gaming, calling it "the mainstream of [future] gaming".