There are a number of Minecraft players unhappy with the RPG elements recently added to the game, in the form of potion brewing, enchanting, and a dragon boss to fight.
The RPG stuff didn't make Notch rich and famous, since it wasn't in the game yet when it went viral.
Had he started with brewing, enchanting, and the dragon fight, he'd still be toiling in obscurity.
Exploring the procedurally-generated world to find a good site for a base, then building it up and staying safe from the bad guys is what made the game compelling for many of us. For a long time Minecraft was about this, as it was what had been implemented before the RPG stuff was tacked on. It doesn't matter to us that Notch ultimately intended to make an RPG when for months what he'd delivered was a survival builder.
With Railroad Tycoon, Sid Meier inspired the creation of many other business simulation games (often with the name "Tycoon" in them), but besides a single sequel many years later (Sid Meier's Railroads), he only did the one. I think Notch is a game designer in the mold of Sid Meier, the pioneering trailblazer who never stays too long in any one place. You can kind of see this from his recent blog Inspiration, motivation, stress, and abandonment.
So on the way to completing his RPG, Notch invented a new category of game that he doesn't intend to pursue. Survival builder set in a procedurally-generated fully editable voxel-based world is a mouthful, so maybe the category will become known as voxel-based survival builders. In the same way that Railroad Tycoon is seen as the original Tycoon game with the railroad theme being incidental, years from now Minecraft may be known as the first survival builder, with oh yeah, some RPG elements.
Since gross revenues from Mindcraft are approaching 100 million dollars, Mojang will have competition, even if it's not from the big companies (see The game’s industry’s massive fail: where are all the Minecraft clones?). It's a perfect opportunity for other independent developers.
While it stinks that we can't have them now, in a year or two I think that several voxel-based survival builders will be available.
[Most of the text of this article originally appeared in a comment on the Minecraft Forums.]