[sokoloff]

Somewhat ironically, it's to make architects' jobs easier when they're drawing things to <architectural> scale.

If you're making a floor plan drawing at 1:100, a 240 inch wall becomes 2.4 inches on the drawing. The scales [of the drawings] and the scales [the tools] evolved together. (Similar to "why do computer people work in base 2 or base 16 so often?")

[jcgrillo]

Makes sense, I'll try to work in whole number scaled inches more (although tbh I'm just being picky, eyeballing the fractional part is usually good enough).