It makes sense, but it means when they went to make Minecraft Pocket for iOS they had to re-write. Must have been a tough decision to force themselves into another re-write when they inevitably want to bring 0x10c to iOS.
More impressively if you use C# you can release cross platform using mono.
With the depth of this game and the FPS type elements though I'm skeptical whether it will make a good iPhone game or not though.