And shouldn’t it be possible to make the battery smaller with a more efficient motor?

It is not indicated anywhere that this particular motor is more efficient than older ones in terms of the electric force conversion.

This new motor is more powerful, that's it.

Nothing was said about cooling or voltage requirements. The latter is important because higher voltage is more dangerous to work with or be near.

The battery could be made smaller by whatever amount is needed to carry the marginal motor weight the advertised distance.