The early use of pi was calculating area and it was derived based on that. At least as far as history can tell us. Records are a little sketchy that far back.
The argument in favour of tau in the formula for the area of a circle is this: To find the area of a circle with radius r, you integrate the circumference of every circle with radius between 0 and r. The integral of tau*r with respect to r is 1/2 tau r^2. Since 1/2 ax^2 is such a common form when dealing with integrals, it can be easier to remember this way.
That's a weak argument. Integrating 2a * x is also insanely common in dealing with integrals. And really if you're deriving the area of a circle and integrating 2pi * r gives you pause you're not on a good road to begin with and removing a 2 from some equations isn't going to help much.
edit: forgot that * would make everything italicized.
lol. I always wonder how people find these things.
Incidentally, I recently read an article about how the creators of The Simpsons actually held math degrees. They hid mathematical easter-eggs all over their episodes. One gag was a "solution" to Fermat's last theorem where 1782^12 + 1841^12 = 1922^12. It's valid up to like, the twelfth significant digit.
