A power-off button is redundant on a digital wrist watch.
On a wrist watch, every button is costly. It is an additional part that can fail or be misused – a chink in the device’s armour. Instead, digital watches are designed to run around the clock (literally) with minimal power. If the watch has a backlight, a button can be used to trigger it for a few seconds.
Yet, if you designed a digital watch with a power-off button, certain users will find creative, meaningful ways to put it to use. If you later decide to remove the power-button in the next version, these users will grumble and give it one-star reviews: ‘The power-button was this watch’s only redeeming feature. And now, it’s gone! — 1 star–‘
We are attached to seeing the world a certain way. We now live in an era where digital wrist watches themselves are redundant. Yet, people continue to buy them.
To design something is a decision to piss a certain group of people off. The only question a designer needs to ask is if they are pissing the right people off.