Celsius isn't granular enough. Many digital thermostats will even add decimal places if you switch to Celsius mode that aren't present in Fahrenheit.
Secondly, the highest temperature ever recorded outdoors was 56.7˚C. So no matter where you are, from that to 99 is wasted.
I have a kitchen thermometer for making caramel (can't remember exact number but ballpark is 200C). I occasionally use my oven at 250C. My wife fires her ceramics in a kiln at around 1000C. I don't feel like I'm "wasting" anything here.
> Celsius isn't granular enough.
This argument would be reasonable if we didn't have to cut inches into 16 or 32 parts to approach decent granularity. At least we use decimal for cutting Celsius up...