What on earth is "the typical minimum temperature that can be tolerated by humans" though? There are people who seem fine living in parts of the world where it's regularly -30C (somewhat less than 0F), and many of us that would find anything much less than 0C (32F!) regularly to be pretty much intolerable. Resolution is an issue for measuring fever, so we use a single decimal point (36.8 is normal, 37.1 is elevated etc.). Other than that it just never comes up. Agreed that 100C being the boiling point of water isn't that useful for setting oven temperature etc., but at least you know something that's 100C is going to be as hot to touch as putting your hand under scolding water (and likewise 0C is going to be as cold as ice. You're willing to sacrifice that?). Kelvin is far easier to mentally convert to Celsius than Fahrenheit, and at any rate Celsius is still used extensively by biologists, behavioral scientists etc.