According to Wikipedia the acronym KISS means “Keep it simple, stupid” and was a design principle noted by the U.S. Navy in 1960.
The KISS principle states that most systems work best if they are kept simple rather than made complicated; therefore simplicity should be a key goal in design and unnecessary complexity should be avoided. The phrase has been associated with aircraft engineer Kelly Johnson (1910–1990). The term “KISS principle” was in popular use by 1970. Variations on the phrase include “Keep it Simple, Silly”, “keep it short and simple”, “keep it simple and straightforward” and “keep it small and simple”.
I’m usually reminded of the KISS principle when I see a forecast or analysis chart from the Met Office similar to the one above (fig 1), for some reason. You could argue, that a set of forecast charts is a system in its own right, and if it is, then why over complicate it? Met Office charts in the past weren’t always as complicated as they seem to be today, but try as I may, I can’t find any images of fax charts from the past on the internet to illustrate that fact.