Common sense is a fallacy. It's a single minded association that has no basis in the true nature of reality.
Anyway, short of hard figures on Nintendo's manufactured units versus physically shipped units and manufacturing capacity, you can only speculate on what is actually happening with the supply. I'll eat a cookie if I'm wrong but...I seriously don't think that Nintendo would cripple their supply on purpose. Being able to say that "all units are sold out" does not impress stakeholders as much as actual high sales numbers. If we completely sold out of Widget X but sold less widgets than our competitors, that will not be as good as if we outsold our competitors, on every level, but still have unsold units in the supply chain. The bottom line is really the most important thing.
You can talk about consumer psychology... If Wii's are always sold out and you see one on the shelf, you'll be more likely to buy a Wii on impulse...because you may not get that chance again. However, it would otherwise be a differed purchase. If Wii's are readily available, you don't have that same sense of urgency. However, like I said before, unless you are a speculator, you are not going to buy a Wii unless you already want one. If you don't want a Wii, you are not going to suddenly buy one just because it is rare and you see it on the shelf.
The only thing that I could possibly see happening, in the supply situation, is that Nintendo may be holding out on manufactured units long enough to ship in a bulk quantity. It is far cheaper to ship and distribute units in large numbers than in tiny batches. Nintendo can get bulk units out to the "local" warehouses and then distribute a steady, albeit small, stream from there. It's much more profitable to use that distribution model.
