1) The game started off life as a regular platformer.
2) Banjo's waaay out of shape.
3) Banjo pushes the 360 but there's still room for more
4) You don't have unlimited creational power
5) There are some jokes in Banjo Kazooie: Nuts and Bolts about Grabbed By The Ghoulies 2.
6) Kazooie is a girl
7) Once you've built a vehicle and got into the game, you can still tinker with it.
8) Banjo isn't actually 'blocky' at all
9) The game often pits you against the physics, not the level