> it tells you nothing about the absolute size of the motor.

No, it tells you nothing about the absolute size of the motor, but for the rest of us, the context clues are there to gain additional information. Someone else constructing something that obfuscates this with a micro-motor doesn't make this useless.

Significant figures exist for a reason. You are ignoring that here and creating precision that does not exist. The kilo-prefix absolutely communicates scale information to most readers.

Similarly it is useful to talk about household electricity consumption in terms of kWh/day, despite that also being a ratio that can reduce down.

The goal here is communication, not theoretical mathematical optimality that is actually worse in every real way.