I get where you're coming from on this, but there's also a need for some perspective here. This isn't Microsoft releasing an OS that has to run on tens of thousands of possible different hardware configurations with varying extremes of performance capabilities, and be able to flawlessly work with decades of software. Nintendo controls the horizontal and the vertical the hardware itself, the software that is released for the hardware, and the OS.
As far as the timeframe, Nintendo has been working on the Wii U since the release of the Wii. The Wii launched in 2006. Nintendo's had six years to figure out how the OS on their new console is going to work.
I'd say that the consumer's "I expect this to just work" is the only relevant issue; the consumer doesn't care how complex the OS is, what's going on under the hood of the Wii U, etc. If Nintendo can't meet consumer expectations, Nintendo has competence problems. Hopefully they are just growing pains and will be ironed out soon.