It looks like that formula is a lot like cutting the ends off the roast.

The answer to "who cares?" is most likely "some 1930s era engineer/scientist who has a great set of log tables available but no computer or calculator".

I am just young enough that by the time I understood what logarithms were, one could buy a basic scientific calculator for what a middle class family would trivially spend on their geeky kid. I remember finding an old engineer's handbook of my dad's with tables and tables of logarithms and various probabilistic distribution numbers, it was like a great musty treasure trove of magical numbers to figure out what they meant.

I don't know where that ended up, but I still have his slide rule.

Of course, even in the day, it would make more sense to share both formula, or simply teach all students enough math to do what Gray does above and figure out for yourself how to calculate the model-enlightening formula with log tables. Since you'd need that skill to do a million other things in that environment.