It's not about what humans "like," it's about the human bodies' internal operating temperature and using that as a reference point, the same way that Celsius is about the states of matter of water . Fahrenheit is useful in medicine for that reason, while Celsius is useful anytime a comparison to water is helpful, and beyond that, it's really just whatever you grew up with. Using a system based on what water "likes" is equally as useless unless you grew up using it as your reference point for temperature in your daily life. Neither 75 Fahrenheit or 23.8889 Celsius tell me whether or not I'm going to need a jacket today unless I've already experienced said temperature and use that scale in my daily life.