I think that it is significant to see Tom as the main character of the drama for a couple of reasons. The first is that if Tom is seen as the main character, it helps to enhance Williams' idea that personal happiness and contentment is not something absolute. When Tom leaves, it is acting upon the idea that individuals find happiness when they take matters into their own hands, do something about their condition, and depart. Tom's presence as the main character, the individual telling the story to the reader, repudiates this because we understand his fundamental unhappiness at his being in the world. Even though he has left, he is still unhappy, demonstrating the reason he is telling the story of his own experiences and those of his family. Another reason it is significant that Tom be seen as the main character is because the reader ends up absorbing the view of the family from his point of view. As Tom tells the story, and as we understand him from the start of the drama to the end of it, the reader recognizes that we end up absorbing his own view of the family from this point of view. It is not something the reader would do if Tom were not seen as a primary, if not the main, character. It is for this reason that Tom's presence as the main character becomes significant as it helps form our view of the drama and the characters in it.