48215 I've only actually used Kelvin maybe once or twice, and I basically just assumed that definition based on how I remember using it :P. In general, Celsius is far more practical than Kelvin. I was also mostly talking about the whole Imperial system (inches, miles, gallons, etc.) rather than just temperature. I can't imagine how frustrating it must be working with those measurements, even if you grew up used to them.
Even where I am just a bit outside the U.S., we tend to use feet/inches for people's height and pounds for weight. I've been slowly trying to teach myself to automatically use Metric for those things, because giving a height in feet and inches seems silly XD.