The opening is a period of time where the position is at its most dynamic. There is a ton of open space to be filled by pawns and pieces, and long term static advantages will be had by the player who best controls the center, because it gives him the space to maneuver from wing to wing later in the game, while restricting his opponents ability to do the same.
Pieces like to operate behind their pawn chains, and flank pawn moves don't contribute to maneuverability. Typically flank pawns are used later in a game to disrupt the opponents pawn chains, to open files for major pieces, and to spear thrust at a king's pawn shield.
Moving the knight to an edge has a double whammy negative, as it fails to support central pawns, and cuts down on the number of squares controlled by the knight. For instance, a knight on f3 projects on four squares of its opponent, and four retreat squares of his own... while a knight on h3 cuts both those numbers in half.
Bringing a queen out too early provides your opponent with a target to develop his pawns and pieces. If your opponent is able to both attack your queen and put pieces and pawns on useful squares at the same time, they have basically been given free extra moves while you are moving your queen to prevent it from being captured.