A better SoC usually means better power efficiency, where the speed means it can get through tasks faster under the same wattage, so it helps battery life.
Which is then completely blown by the screen anyways? It's not like you're tearing up complicated calculations on your watch. This makes sense on other devices but not so much on a watch. My Garmin lasts a week with the screen always on, several hours of GPS on and music playing during workouts. The most draining thing is music.
Yes but those screen features are what some people ask for (and always on can be disabled).
The watch also does do quite a bit of processing on device, especially cellular ones. It's quite a different beast than the Garmin, even though they have crossover