Often photographers will complain about point and shoot cameras, and if you let them go on long enough they'll talk about camera flashes. What would a photographer have against camera flashes? Camera flashes have a tendency to flatten a picture, removing the illusion of form.
Artists, too, do not generally use lighting from straight on. The lighting has its place in folk art and was used in some illustrations to create a simple quaint look, but whenever artists are trying to create any type of drama, they choose another way to light the scene.
Let me show you what I'm talking about.
This is a ball shown with straight on lighting. It's sufficient to show that this sphere has form, but just barely. As a sphere, it's not much too look at.
If we move the light all the way to the other side of the ball, it creates an effect like this. This is called backlighting. Original, isn't it? This is the king of dramatic lighting—not much for form, so what is shown had better be significant.
To move the light to the side of the ball, creates an effect like this. This light source is slightly behind the ball.
This lighting will be most used. The light sits in front and to the side of your subject. This accents the form, shows the colors, and makes the detail visible.
To further examine these lightings, I made a little experiment. Using my own face as a source, I made a hobbit face and then "lit" it in different ways. I don't really know why I chose a hobbit, but if I had to do it over again, I'd choose a different source. It just feels strange and narcissistic to paint my own face as a hobbit face in different lightings. My only consolation is that someone might learn something from the following middle earth sillyness.
This lighting is from straight on. The lighting has its place, but generally is not as effective as other ways to light a subject.
Here is backlighting. Notice how much of the details disappear and the mystery and drama is majorly heightened.
This is side lighting. This shows the form fairly well, but something bugs me about this type of lighting. Sometimes that kind of uneasy emotion is great for drama, but more often than not three-quarter lighting will be better.
Last, but certainly not least, this is three-quarter lighting. This is the work horse of most works of art through the ages. As I said before, three-quarter lighting shows off the form, the colors, and the detail very well. As an artist you will probably light your subjects like this often, but from personal experience I sincerely hope that you will not be repeatedly drawing your face as a hobbit in this lighting....