I think that I've realised why you might calculate pi. It's easy$\pi$.
x^2 + y^2 = 1It's easy: $x^2 + y^2 = 1$ is a simple calculation, thus fast. IfIf you pickedwould pick another 2 dimensional shape with a non trivial perimeter, you'dyou'ld have a harder time estimating which side of the perimeter a point had fallen.