It should be noted here that the daily high for a good 1/3-1/2 of America is below 0C/32F/freezing for a good 3-5 months each year. Our weather varies much more significantly than most (not all) of Europe. Even with Fahrenheit, it is not uncommon for places like Detroit to be sub-zero for days without getting into positive temperatures.

I've personally lived in Marquette, Michigan and now live in Phoenix, Arizona and have experience both -40F(-40C) and 118F(47.7C). To me, the 0 = really cold, 25 = cold, 50 = mild, 75 = comfortable, 100 = really hot scale makes sense having lived through those extremes. But you're right, that's largely because it's what I grew up with. And with that in mind, it is extremely unlikely America would ever transition away from it for that very reason.