[flowerthoughts]

This still falls under the "but we're used to it" argument. That notion that it feels natural, I argue, is a result of you having seen both W and Wh in enough contexts that you start building intuition for them. Had we had W and J, you would have been able to build the same intuition.

> If you said 1MW/360GJ, I don't think that would be nearly as clear.

Wouldn't have been using the hour as the mental reference. As you say, it's impractical. We would have probably rounded the 86,400 seconds in a day to 100,000 and used that as the reference for comparisons. There's nothing noteworthy about the hour in this context.

> A battery that provides 1 amp (at 12V, but that's already given in a system) for 50 hours. Makes immediate practical sense, especially when equipment is often labelled in current draw and you can measure amps with an ammeter. 2.16MJ far less so.

I argued Ah could have used the SI base unit C, not that we'd use J. Whether you count As or Ah is still just a matter of building intuition.