Why the guard position is so important?

The guard position is very important. There will always be a tendency to slacken this as you focus, as a beginner. But in a contest or actual fight, this cannot be allowed, which is why practicing this properly is very important. The hands also must move up and down constantly covering the face to protect with from any unexpected punch or kick.
What are the areas you are protecting with your hand position?

• Bridge of nose -- causes a lot of interesting bleeding if hit.
• Lips -- again very soft target, easy target. These are also spots u seek to hit while aiming.
• Chin.
  
• Neck.
  

Ideally when u hold the hands in front of your face, give enough space between both hands to see your target. Always keep your eyes on him. This will prepare you to read his mind and help u unconsciously move your hands to protect yourself from his attack. Right hand, clenched is towards your nose. Left hand, also clenched, is away. The shoulders must be rounded to take any hit, while the elbows lightly flared to protect the armpit...

More on this later