Whoever came up with the aperture nomenclature.....

This business of f/xx is just plain asinine. Yes, I understand what it represents. Yes, I understand that the larger the denominator, the smaller the aperture. Yes, I understand the significance of the aperture size, etc. etc. And I even understand that the amount of light reaching the film/sensor is also dependent upon the focal length, and that f/4 on a 100mm lens transmits a different amount of light than f/4 on a 300mm lens.

But what I’m wondering is why on Earth does the aperture size need to be expressed as a fraction of the focal length? Why couldn’t they simply list it as a diameter in millimeters? This is far more intuitive and, quite frankly, useful, since the focal length of a lens is always available to us.