Eagleland doesn't need yer fancy metric system that makes sense! We have our arbitrary, retarded Imperial system that doesn't make any god damned sense!
It's not a metric vs Imperial thing. I mean, yes, technically the SI unit for angles is the radian but degrees are accepted for use with SI, and they're what every country, whether they use metric or not, starts with for schoolkids. Radians are more mathematically elegant if you're doing anything with trigonometric functions, but not quite as useful for everyday stuff or engineering because all the standard angles are irrational numbers (fractions of pi, specifically).
As a general rule, mathematicians and physicists use radians but pretty much everyone else uses degrees as far as I know.