If you drive more than one vehicle on a regular basis, you might be acutely aware of varying pedal movement which can cause you to brake either too early, too late or not hard enough.
Apart from the obvious inconvenience of this kind of driving, a pedal going down too far before the brakes bite might also be a hidden warning of a much more serious problem in the brake system itself, which by the way is also checked during an intermediate service. And pedals set too high prevents the driver from executing all the force that might be needed in an emergency situation, so it has to be set correctly.