Stretching is to fighting what bacon is to life. Both can happen without it but with it they acquire a special cadence. Stretching helps you warm up a little. It conditions your muscles to stretching and contracting movements which best prepare them for action. It also helps increase your flexibility which, in turn, makes you faster and more powerful without an attendant increase in muscle mass. If you get into the habit of stretching regularly you will see an increase in your body's performance capabilities, naturally.
Extra Credit: Hold side splits for 60 seconds.