Because negative 7 is technically lower than negative 5. Due to them being negative the more closer you are to -1 the more higher of a number it is. I don't know how to explain it but I hope that it makes sense!
Centimeters might be easier because they can be much more precise than inches when there isn't an ideal length. Kilometers might be easier because it would not require such large numbers to work with.
I think they should keep it around, even if it might not be the most efficient strategy. After all, what if you need to solve a problem using multiple strategies?
