To a great degree, price-points are defined by BOM - the Bill of Materials. On the plus side, Wii U benefits from a significantly more modern graphics core, equated by many with an entry-level enthusiast GPU a couple of generations old, provided by AMD. Our sources tell us that the hardware is rich in features compared to the Xenos core within the Xbox 360 (also supplied by AMD) but somewhat lacking in sheer horsepower: still a useful upgrade overall though. However, on the flipside, the tri-core IBM "Espresso" CPU is an acknowledged weakness compared to the current-gen consoles - the processors consisting of revised, upgraded versions of the Wii's Broadway architecture, in itself an overclocked version of the main core at the heart of the ancient GameCube. Nintendo clearly hoped that tripling up on cores, upping clock speed and adding useful features such as out of order execution would do the trick, but key developers are saying otherwise: GPU-heavy games get a boost, but CPU-dependent titles are challenging to bring over to the new platform. Debate still rages over the extent to which Wii U is a next-gen console at all, and whether its pricing fits accordingly.
The overall conclusion one can draw from the core components here is that Nintendo hasn't really paid so much attention to competitive forces, targeting a spec that can be mass-produced relatively cheaply. Areas where we know Nintendo easily outperforms Xbox 360 come to down commodity items such as RAM and flash storage: these are upgrades that won't significantly affect the bottom line.
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Of course, Nintendo's key point of differentiation is the tablet controller - which obviously adds to the bill of materials, but once again we see a piece of technology built to a price. In a world where Chinese no-name manufacturers can develop capacitive 7-inch touchscreen Android tablets with ARM processors, 8GB of flash storage and 512MB/1GB of RAM priced at £50-£60, Nintendo's resistive screen tablet produced in the millions would clearly be significantly cheaper to mass-manufacture - even factoring in the latency free AV transmission tech.