This doesn't look like a N64 game (unlike Crusin') but it does look like it was developed by a team with inexperienced texture artists and bad modelers ...
Back in the day you would see good modders of games like Unreal Tournament produce models with 450 polygons and 96x96 pixel textures which were similar in appearance to what an average modder could produce using a 600 polygon model and a 160x160 pixel texture; and a bad modder would require 800 polygons and a 256x256 pixel texture.
Quite possibly this game could look so badly because it wasn't really designed to run on the Wii. I don't really know the history of this game but I wouldn't be surprised if it was the port of an average PS2 game, or if they downgraded an XBox 360/PS3 game and the visuals demonstrate how inefficient they game ends up being.
