As you said, it's occasional. Temperature describes weather more often than anything else. And there's no advantage to Celsius for the ovens either.

Yup, because neither has significant advantage over the other. The only place where Celsius imo has a slight advantage comes from how often the phrase "below freezing" is used when talking about weather. That to me suggests that 0C/32F has some special significance, and thus makes Celsius a bit more elegant because it acknowledges that point. The granularity doesn't matter too much, as long as we agree to use decimals for ease of calculations, instead of using 1/32nds or some other barleycorns.