You would bring an umbrella for a 50% chance of rain, so why wouldn't you bring a flashlight for 100% chance of darkness every night? Why should one bother weighing themselves down with something that seems so unnecessary?
The short answer is: power will fail you.
It doesn’t matter how many carrots you eat; you will never have natural night vision. And since you probably aren’t going to wear an infrared rig every time the sun goes down or you enter a dark room, having something to light your way can be indispensable. From getting through power outages, to looking under couches, to navigating a dimly lit path, having a light source in your pocket will come in handy. Some might be content with using their phone’s screen or camera flash for light. Modern lights, with multiple modes and a dedicated battery, perform far better in daily tasks to emergency situations without draining your phone’s battery even more, making them a must-have in many carries.
Flashlights and lanterns are a convenient, practical, fun and lightweight tool that you can keep in your briefcase, carry to the park, put on your keychain and even in your pocket. Flashlights can allow you to be in control of everyday situations. Getting caught in the dark is inevitable. Always be prepared, and even better, be equipped for the unexpected.