Having a quality watch to track your runs is important to runners - of all levels. You want to be able to accurately track your time and/or distance and/or speed. (Some runners do some workouts only for time and others do all their runs for distance.
During the day, it's easy to glance at your watch and see what time it is. At night or when encased in darkness, seeing the time becomes a lot more challenging. Today's watches may have a button to press that will make the face light up so that the time can be seen but not all of them do.