Why would they? Producing cheap hardware that is based on "withered technology" (Gunpei Yokoi) was a success for their entire handheld line and Nintendo's best selling consoles (Wii and NES, which competed with home computers) were both underpowered for their time.
I know hardcore gamers make up all kinds of theories about why Nintendo's product are successful or not but for investors it's pretty simple: Whenever Nintendo produced a mass market friendly device (and supported it with mass market friendly software) the company thrived: NES, SNES, Wii, GB(C), GBA, DS.
Nintendo is a company like Disney: They need to target a big audience and they have a family friendly image. Producing expensive consoles with a focus on "3D Gaming" or "Hardcore Gamers" or "Third Party Support" simply won't help them. What they need to produce is a quality console with quality software for the mass market. Just like the Wii was.