In years past, Mario showed up in a bunch of Nintendo games. Tons.
"Mario is a very important character in the Nintendo world and so we want him to appear in our titles," said Miyamoto in a recent interview. "Indeed there are a lot of games to which he is well-suited. However if he appears in too many games then they will lose their uniqueness, and so with that we are very strict when choosing which games to have Mario feature in."
This conflicts *somewhat* with what Miyamoto said last fall. Perhaps Miyamoto was talking about the future?
"My plan was to use the same character in every video game I made," Miyamoto said late last year on the official Nintendo site. The idea to put Mario in multiple games wasn't simply clever branding on Miyamoto's part: he was influenced by Hollywood film director Alfred Hitchcock. "I thought the way Hitchcock cropped up in all the films he directed was really cool!" Miyamoto was also influenced by manga artists like Osamu Tezuka (Astro Boy) and Fujio Akatsuka (Tensai Bakabon), who put their characters in multiple works.