Comment by HPsquared

The calculation in the metric system would not necessarily be more complicated, but it would be different because the reference points in the metric system are not directly aligned with the geography of the Earth.

"1 knot is about 100 ft/min which is very convenient for descent at a specific glide slope (i.e. for 100 knots ground speed at 5% slope you want 500 ft/min descent rate). Standard is 3° which is about 5%."

You are right. It's an easy calculation. But I would say its easy because its historically based on imperial units. Its easy to think about easy calculations like this in metric units like:

A 5% slope means descending 1 meter vertically for every 20 meters horizontally.

I suspect that the math is even easier using meters, meters, and meters per second than nautical miles, feet, and knots. I'll eat my hat if you can tell me the conversion from feet or inches to nautical miles without looking it up

who is flying exactly north/south?

This sums it up. Metric is nice and clean tenths, but the real world is seldomly easily expressed in clean tenths.

Another example: The feet is cleanly divisible in thirds, quarters, and twelfths, which is greatly appreciated in industry and particularly construction.

Also to be bluntly mundane, almost everyone can just look down and have a rough measure of a foot which is good enough for daily use.

Also, the "sterility" of metric doesn't do it any sentimental favours. Japan loves measuring size/volume in Tokyo Domes, for example.