"After a large-scale test of a prototype inside the company, we found out that for some people the sensor did not work as expected," Nintendo global president Satoru Iwata said during a meeting with investors, after being asked for a status update on the product.
"We wondered if we should commercialize a product which works as expected for 90 people out of 100, but not so for the other 10 people," he continued. "Though I am sorry that we did not give any specific updates after this product's initial announcement, I would say that knowing that a product has a problem we should not launch it for the sole reason that we have already announced it."
Iwata also added that, even when the sensor functioned as expected, "it was of narrower application than we [read: Nintendo] had originally thought." The Wii Vitality Sensor (or something like it) may eventually make it to market, providing that the technology advances to such a degree that "999 of 1,000 people to use it without any problems, not only 90 out of 100 people."