And that's MediaMarkt for you. They ship in big quantities, and their shipments fluctuate.
When I was looking for my current 40" Samsung LCD, they had at the very least some 250 on display in one store (and quite a few more in the warehouse, since they specifically advised me not to take one of the boxes on display and instead take one from the warehouse, which I did). Incidentally, they hadn't a single unit on display in a store just 10km away. And this is a ~100x70x30cm box we're talking.
Besides, most of Europe hasn't really been a problem in terms of Wii stock, if you're a just little persistent. And with the strong Euro, it actually makes perfect sense to make sure Europe is permanently well stocked (not overstocked, but well stocked), even if the US market has a stronger potential. Lets not forget that most European consumers now pay $400 or more for a Wii.
Reality has a Nintendo bias.