So it's widely known as a fact that many Nintendo games have ridiculous legs. But here's the question that no one really bother to ask...why is this so?

[Mythmaker1]

Infrequency of sequels, pretty much. And lack of competition on the platform.

On the Xbox 360 and Playstation 3, publishers have very little time to recoup their money because there are so many big names. It's why small-fry devs avoid the Chrismas season if they have any sense; they get crushed by the newest iteration of franchise X, Y, and Z. Or take these last few months. Some fairly big-name games have come out, and most of them have already faded out of the public consciousness due to new releases.

Nintendo doesn't have any serious competition, in this regard. The home-field advantage makes them a bigger player on their own platform than any competitor could possible hope to match. Other consoles, because they have a smaller individual presence, are on a more even playing field, and so compete much more.

And for the same reason, publishers on 360 and PS3 release more sequels. They have to, if they want to stay relevant in the market. Which means the last game they released is usually made outdated pretty quickly.

Nintendo, because it doesn't have to compete against any other big names, can take its time, confident in the knowledge that nothing its competition can put out will be able to compete with its own franchises.