Where you look is important, not just to keep from walking into telephone poles or driving over your neighbour's pug but also when performing Karate. The beginner Karate student does not usually pay attention to where they are looking when performing a kick or punch. When I was first introduced to this concept I too was skeptical of its importance. However, I soon learned otherwise when practicing applications or bunkai.
So I practised Hen Chu Ho with metsuke(pronounced "met-ski") and it seemed that the direction of my gaze affected my body posture. My improved posture put my opponent further into Kasushi (off balance) than without proper metsuke. With this improved kasushi I was able to throw my opponent with greater ease.
Metsuke refers to gaze or focus point. Often I have heard the term "look at the mountains". In this case it refers to looking at the whole body of my opponent and not focusing on their arms or feet. In a way, it is looking at something without focusing on a single point.
So it helps me improve my bunkai technique but there are other applications of metsuke.
In sparring your facial expression affects your opponent. Churchill once said: "I like a man who smiles when he fights". I am not sure I agree with smiling in the sparring ring (someone might call a therapist for you) but metsuke in this case refers to two things. How you view what your opponent is doing and how your opponent perceives your confidence during the competition.
When sparring I avoid staring at my opponents feet or hands. Often I try to look past my opponent through their eyes. This way, my peripheral view will catch all arm and leg movement, and their eye movement will divulge their intentions.
In the second case, a calm, impassive face is considered the ideal situation.
http://web.mit.edu/jpnet/ji/data/4460.html
http://web.mit.edu/jpnet/ji/data/4153.html
