It comes down to familiarity, but -20 to 40 degrees Celsius isn't that weird a scale, either. You're going to remember more or less arbitrary values for certain things anyway (too hot to be comfortably outside, cold enough to need a jacket, cold enough to need gloves, cold enough to need multiple layers, etc.). In that sense, yeah, Kelvin would be impractical, as would be a theoretical temperature scale that compressed most human-relevant temperatures between 0 and 2 or so. But that's not the case and degrees Celsius is perfectly viable for everyday use, as is (I imagine and you say) degrees Fahrenheit.