As I always say in these debates:
1 -- Except for temperature (the degrees are just too big), the metric system is better worked out than the American, easier to use in many applicatoins, etc.
2 -- The purpose of the encyclopedia is not to make people better, it is to impart information to readers.
3 -- Millions of American encyclopedia readers cannot do the conversions in their heads and should be provided with useful information on the height and weight of the hippopotamus.
Apropos Jimbo's point about the superiority of the American system, as in the case of temperature, the American system is superior on account of its stronger relationship to the human scale, an inch is a knuckle, a yard is a pace, a foot is as long as a foot, a mile is a long walk, and our zero degrees is actually cold and not just brisk and our 100 degrees is body temperature.
On the other hand, a system that goes from 1/16 to 1/8 to 1/4 to 5/16 to 3/8 etc can really wear you out. And 40 below zero is cold no matter how you count it.
Tom Parmenter Ortolan88