4-3-3 increases the number of touches each individual gets on the ball, its the same reasoning behind small-sided games. The more touches a player gets the more time with the ball he/she has the more technical/skillful that player is going to become.
Con Boutzanis (sp?) - released his own training "app", in which a beginner player would recieve over 500 touches an hour and an expert player between 1000-1500. Giving players far more time to develop with the ball.
We are trying to move away from the ideology that physical attributes outweigh everything else.