I will start with the following proposition: there is nothing cooler than ninjas. Therefore, a ninja game allows a console to reach its peak coolness.
The purpose of a ninja, as we all know, is to flip out and kill people. [source: realultimatepower.net]
Now, check this out. Nintendo's implementation of a ninja: Goemon aka 'the mystical ninja'.
I rest my case; only Nintendo could fall so short of the full ninja-glory. A true ninja would kill anything that looked like that -- including itself.
Also, they are porting this god-awful thing to the DS. Proving that Nintendo was not 'just experimenting'.
*edit* I'm not sure if that thing is actually suppposed to be a ninja. Nonetheless, it is a ninja game, and it does not die.