Why did Jesus defend the disciples' failure to wash hands prior to eating? (Catholic perspective)

In Matthew 15:1–4 we see: > Then Pharisees and scribes came to Jesus from Jerusalem and said, “Why do your disciples break the tradition of the elders? For they do not wash their hands before they eat.” He answered them, “And why do you break the commandment of God for the sake of your tradition? For God said, ‘Honor your father and your mother,’ and, ‘Whoever speaks evil of father or mother must surely die.’" We see Jesus virtually defending the disciples who had failed in following a simple lesson of hygiene in an age when food was eaten directly with hand and not with the help of spoon and fork. Of course, Jesus was trying to bring the Pharisees home to more important things of life. But then, He could have started like this: "Well, I agree that my disciples are too old to be taught table manners, but..." My question is: How does the Catholic Church explain the lack of importance attributed by Jesus to the washing of hand prior to eating by His disciples, in the face of criticism by the Pharisees?