The protagonist, Philip Hoffman, is directing the play 'Death of a Salesman' with a twist. He is casting young actors as the characters of Willy and his wife. From my understanding, he is doing this to portray how young people are facing the same dilemmas of rejection and probably failure much earlier in today's life. Is there some other reason the director/writer of the movie Charlie Kaufman has used this play in this movie?
My interpretation of Hoffman's character Caden is that he is struggling with the purpose and apparent futility of life and is trying to understand it, to capture the essence of life in a single piece of art. His attempts become bloated and spiral out of control because he is trying to explain the unexplainable.
Seems to me he is tackling the same problem with his interpretation of Death of a Salesman. I think it is less of a statement on today's society being harder for younger people than it used to, and more about the universality of struggle. Caden views everybody, young and old, as rocketing towards death and insists they should find meaning in their lives before they die.
There are also a few parallels between Salesman and Synecdoche, mainly in their leading characters. I think Willy and Caden are both a little deluded; they are not as good at what they do as they want to believe. As both approach the end of their lives they worry that they haven't made much of an impact. Willy is so heavily invested in his job that he is broken when he is fired, and similarly Caden so obsessively pursues the meaning of life in his play that he doesn't end up creating anything meaningful. However, the similarities between the two works don't run much deeper than that.