It makes sense for Tom to narrate the play, because the other main characters possess personality flaws that would make their ability to narrate more problematic. Amanda lives in a dream world, stuck in the past, and Laura is painfully shy and inexperienced with social interactions. Tom has a dreamy quality, and fancies himself a poet. He is also very frustrated with his life at home and longs to get away from it, in particular his difficult relationship with his mother. The fact that Tom's main action in the play is to gain the motivation he needs to leave home already means his character is slightly removed from the action, which also makes him a suitable choice for the play's narrator.