I have always hated this argument. If that were the case, then 50 would be the most comfortable temperature and it's not. This scale is about 20 degrees off since most everybody prefers a temperature of about 70 F.

But that's the same argument that people use against Celsius: "the freezing and boiling points of water is an arbitrary scale, I prefer Fahrenheit because it's more human centric" (Even though it's not). What you're saying is equally as arbitrary, the average temperatures of the planet as a whole is still not a human centric frame of reference.