I didn't even want Galaxy 3. I wanted what Galaxy was to Sunshine, or Sunshine was to Mario 64. And this is Nintendo's first new hardware in over a decade. Do something you couldn't do before, like steal the open world from Jak and Daxter. Instead of levels, there's just one giant seamless world with a natural progression between areas. OK, that's dumb, but Nintendo (allegedly) has creative people to figure it out.
The line of thinking was probably "New Super Mario Bros games sell more than the 3D Marios. Let's make 3D Mario more like New Super Mario Bros!"