None of those things are strictly fundamental. We can do physics with entirely different units with no changes to our formulas as long as we keep the units cons

None of those things are strictly fundamental. We can do physics with entirely different units with no changes to our formulas as long as we keep the units consistent. Those relationships are fundamental. The units are not. But we aren't talking about changing the hour. We are talking about changing the label we attach to a given hour. A better analogy would be changing the word kilogram to something else if we found doing so useful. And, in fact, we do that all the time whenever we are talking in another language.