In short, the bit of time it takes to train and stretch the neck can improve athletic performance, add to your appearance and help prevent injury. If you suffer from tightness caused by long hours sitting on your tail at the office, the stretching alone should make your life more comfortable in general.
Neck muscle groups include (1) Rotators (responsible for rotation): Move the head from side to side, as if to look over the shoulder. (2) Flexors (responsible for flexion): Move the head down, as if to touch the chin to the chest. (3) Lateral Flexors (responsible for lateral flexion): Tilt the head to the side, as if to touch the ear to the shoulder. (4) Extensors (responsible for extension): Tilt the head backward, as if to look skyward.