Man is the Measure of All Things Dept.

From  i.imgur.com via James Grahn via Mother Jones via
Glenn Reynolds  

Growing up with Fahrenheit, then converting to Celsius, is like learning a second language. It's the rare individual who intuits the second as well as she does the first. Besides, as the graphic shows, Fahrenheit is more relatable than either Celsius or Kelvin; human beings can experience both zero degrees and 100 degrees Fahrenheit and live to tell about it.

Other comments:

1) Learning metric so that it's second nature involves re-learning scales for temperature, distance, weights, and volume. So it's like learning four languages.

2) Don't waste your vanishing brain cells on doing something that your phone can accomplish in a few seconds.

3) Forcing happy natives to change: when Americans do it to others it's called cultural imperialism!