That's not really true. But I agree with you, it's very complex to write a 3d game (well even 2d) with GX, if you're not already a comfirmed developper with good C++ and opengl knowledge for ex.
There are very few 3d homebrew games. I'm amazed by
Helium Boy ,
CosmoRaketti, or
Nowhere for instance.
Newo Asteroids is very nice too. Recently,
Build Blocks has been released that looks like minecraft and it's quite impressive. The bad thing is most don't have source code so we can learn from them. Perhaps, they prefer to earn a few $ by porting to shitty android/ios.
But, I admit I prefer 2d games with original concept or nice graphics anyway.
To sum up, wiicraft is maybe too ambitious. Using libs like grrlib (rather simple for 2d) or wired could ease development.