There are a lot of unanswered questions out there in Nintendoland: Why was there never a Metroid 64? Why did cliche villain Wario become a major character, and then only for the Game Boy? What was the Virtual Boy supposed to accomplish? Why was there only a Game Boy follow-up to Kid Icarus? The short answer is "politics".
An article at N-Sider explores these questions by explaining the history of Nintendo's internal development teams and how a recent reorganization of those teams gives legendary game producers such as Shigeru Miyamoto direct access to properties such as Metroid and characters such as Wario for the first time.
Nintendo... promoted several long-time EAD directors to producer roles -- the list of which includes Eiji Aonuma, Hideki Konno, Tadashi Sugiyama, Takao Shimizu, and Shinya Takahashi. Shigeru Miyamoto now completely manages all of Nintendo's internal software development, granting him access to the Metroid and Wario franchises for the first time. The change ultimately bodes well for Nintendo's big picture as far as creativity and productivity are concerned.
The piece concludes with a detailed look at the development team previously known as R&D1, chronicling their time spent developing Super Mario Land, giving Wario a boost to stardom in order to focus on their own creations instead of Miyamoto's borrowed concepts, and reviving the 2D Metroid tradition on the Game Boy Advance after dealing with the loss of producer Gunpei Yokoi.
This is not praise that I hand out often, but if you consider yourself a fan of Nintendo's creations then this is an article not to be missed. It is informative, interesting, and sheds some light on how politics within Nintendo itself shaped the company's policy towards which gaming characters to promote and which to leave in the dustbin over the past twenty years.