A lot of people upon seeing the Wii U controller think that it would operate as a portable gaming unit on its own, though it does not. According to Nintendo CEO Satoru Iwata, making the controller operate separate from the Wii U console was on the table.
“During the roundtable discussions there were such arguments about should we make it capable of being a standalone system or should we make it work only with the [base console] system,” Iwata quipped. “We came to the conclusion that this controller is only going to show the images generated and processed by this hardware unit – and sent from the hardware unit wirelessly. That means sharper graphics. A battery couldn’t do that.”
The LCD screen was also separate from the controller like the Dreamcast VMU. “Considering how expensive screens were then, it did not make sense to have this big-sized LCD,” he said. “We would not have been able to come up with a reasonable price point. We had not decided when we were going to launch the new console [at that point], but we knew we needed to be flexible.”
Source: Gamasutra {link no longer active}
