I am pretty sure they already thought about that.
Option 1: It's coming.
Option 2: There's going to be a redesign of how the Watch is charged and they won't bother.
(..) I can just use the Macbook charger to directly charge the phone. (...).
Say wut? You are using a 25/60/87w adapter to charge your iPhone whilst it can do 12w at maximum? Wouldn't dare to try that, honestly.