Wood is not forgiving. The player must concentrate on a smaller hitting surface. Wood builds strength while perfecting the skill of hitting. In order to be successful as a hitter one must have confidence and working, learning with wood bats builds confidence. Also, knowing a hitter is using the same tools as professionals will enhance confidence.
Wood allows young hitters to swing at pitches they can hit and learn the strike zone.
Metal bats reward hitters for swinging at pitches out of the strike zone or that are inappropriate for the situation. Wood bats are heavier and because by rule they must be solid, the weight is distributed more towards the barrel end. As a result, wood bats are more difficult to accelerate to swing speed. Extra weight makes timing and control more finite. Wood more acutely identifies specific weaknesses in mechanics and magnifies needed adjustments.