Ships and airplanes traditionally navigate using latitude/longitude measurements. Since that coordinate system is based on degrees/minutes/seconds of arc, a length unit that uses the same system is more natural.
And, we don't always adhere to cartesian conventions. Right-hand and left-hand rules abound in engineering. And even computer graphics regularly flips the axis directions depending upon usage (perspective transforms, for example).
And, decimal degrees isn't that uncommon either.