I've been saying this for years. The Earth is egg-shaped and fatter in the southern hemisphere, not a perfect sphere. Logic would dictate that any surface with steep mountains, continental tectonic shifts, and deep trenches is not perfectly spherical. Coincidentally, I have an uncle who was a geodecist and one of the world's GPS experts.
I knew college professors who believed that most map projections have a eurocentric bias, but it makes almost as much sense that creating maps and globes is easier to do if you assume the Earth is a perfect sphere.
Those things, while important to consider if you are trying to do something like hit hit a target within a few kilometers with an ICBM (http://en.wikipedia.org/wiki/International_Geophysical_Year), are not significant when dealing with general purpose mapping.
I knew college professors who believed that most map projections have a eurocentric bias, but it makes almost as much sense that creating maps and globes is easier to do if you assume the Earth is a perfect sphere.