Hitting down on the ball is a misconception fostered, I believe, by a misunderstanding of the dynamics of a correct golf swing.  This can be explained by looking at what happens during the swings of the touring professionals.

     Let me preface this with the premise that the golf swing is a circular motion.  Every circle has a center.  The center of the golf swing is located at the sternum (breast bone).  The bottom of the circle is the point on the ground directly below the sternum and centered between the feet.

     With the turning of the torso and shifting of the weight, the swing center moves slightly behind the center point in the back swing and moves slightly ahead of the center point at impact.  This causes the bottom of the swing to also be ahead of the ball at impact.

      The deepest part of the divot is the true bottom of the swing.. So the pros are not actually hitting down on the ball, they are hitting in front of the ball by virtue of the shifting swing center.  The ball just gets in the way.
The Divot
"Everyone replaces his divot after a perfect shot."
"Never try to keep more than 300 separate thoughts in your mind during your swing."
"The shortest distance between any two points on a golf course is a straight line that passes directly through the centre of a very large tree."
You can hit a two acre fairway 10% of the time and a two inch branch 90% of the time."