3DS hardware producer Hideki Konno discussed why the new portable continues the DS stylus tradition instead of going multi-touch.
Speaking to Joystiq Konno answered: back compatibility. The original DS consoles use resistive touchscreens, where a stylus-like object (or your fingerips) can be used to control the screen. These days capacitive screens which require conductive materials, like a bare finger, are commonplace in devices like tablets, mobile phones etc - allowing for multitouch control.
So why does the 3DS use the same aging screens as the 6-year old DS? The reason being the DS's huge back catalogue of games that Nintendo couldn't give up.
Really, it's all about the backwards compatibility. We have to play DS games on this and we want to make sure they work.
Konno felt that there wasn't currently a feature rich touchscreen that could come close to emulating the DS feel.
Fair enough, but what about the new Wii U - The Wii doesn't require a resistive touchscreen and with Apple's iPad/iPod and other similar capacitive devices being the norm, why does the Wii U use the older touchscreen technology? We're sniffing at possible DS emulation..