Kuyt stressed the Arsenal striker was making a huge contribution and was not the only top attacker to struggle in front of goal.
He said: "People expected Robin to score five or six goals and he hasn't done that - but the way he is playing he is still very important for us.
"He is a quality player but in this World Cup it is very difficult for strikers to get space, create chances and score goals.
"In all the games we have played we've had more space on the flanks. The players on the wings have scored the goals while everyone in the middle is struggling.
"Then if you see David Villa, he is playing on the left and cutting inside and scoring a lot of goals so it looks like it is easier for players on the side to create chances and score.
"But Robin is still very important for us - he works really hard and is a real team player."