I think this explains the superiority of Fahrenheit in terms of use by humans.
Except not quite? I know you are being facetious, but for the few people who read this in earnest:
The 0°C is the exact freezing point of water, whereas 100°C is the exact boiling point of water, which gives a very distinct idea of what is "hot" or "cold" is. Fahrenheit has those values at 32°F and 212°F, which is a bit arbitrary. As for where °F came from, it's is apparently the point at which a mixture of ice, water and ammonium chloride becomes stable, which is again, a very arbitrary and unnecessarily difficult way to express a degree of heat. (Kelvin has an even better way of expressing it, as 0K is simply absolute zero, aka the lowest possible temperature we have knowledge of)
Of course, the "centigrade" system of there being exactly 100 degrees between the boiling point and freezing point of water, (as opposed to 180 with Fahrenheit) allows for easy percentage calculation and scaling without having to resort to decimals (which is, again, weird, considering the temperature difference between 1°C and 2°C is in fact larger than the one between 1°F and 2°F). In fact, Celsius only expresses degrees in decimal numbers if it has to convert from Fahrenheit or express Absolute Zero. ^__^
You may consider it vague, but everyone's perception of "hot" and "cold" have always been that way. The human body isn't made for measuring temperatures ad hoc, as our bodies can only measure relative changes anyway. The point that Celsius is "vague" is therefore moot because it's the exact opposite (and this is ftr also true for Fahrenheit.

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Now the actual reason why Fahrenheit is still used in the US today, despite its difficulty is because it was the first system introduced to measure temperatures. Fahrenheit invented his degree system in 1724, while Celsius invented his in 1742, with Linnaeus finalizing it in 1744. SI chose to adopt Celsius's in part because the British didn't wait for Celsius to finish
his system and had already adopted Fahrenheit by then (and SI is French, meaning they're inclined to do the reverse of whatever the British do. Oh, politics) but mostly because Celsius's system has a lower difficulty curve. (again. 0= freezing, 100= boiling. There's no simpler way of expressing those concepts, really.) Hence why you still use inches, miles, yards, pounds, ounces and other arbitrarily chosen measurements that never made sense to begin with, as opposed to the rest of the world, which adopted SI if given the choice..
TL;DR it's all the fault of the British. *throws large crate of thermometres overboard*
Class in session.