As for the message of needing to let things go, it was best demonstrated with Anakin's mother. Anakin needed to let her go and move on. But he opted to cling to the past and, when it came time for her to die, he was not prepared for it. If he had let her go, he could have come to terms with it and not started down that path to the Dark Side. He would not have clung to Amidala, and the Emperor would not have been able to use the fear of loosing her for his ends.
That is one of the reasons the Jedi shun such material possessions. Greed and fear of loss controls us too much.