Shakespeare's decision to end Hamlet with a tragic ending was likely driven by the play's themes of mortality, revenge, and the consequences of inaction. The play explores the fragility of life and the inevitability of death, as well as the moral and psychological complexities of seeking revenge.
One possible interpretation of the play's tragic ending is that it serves as a warning against the dangers of indecision and inaction. Throughout the play, Hamlet struggles with whether to take revenge against his uncle for the murder of his father. His hesitation ultimately leads to a tragic outcome, as his delay allows for the accumulation of more deaths and for the eventual downfall of himself and those around him.
The play's final scene, in which almost all of the main characters are dead, emphasizes the toll that Hamlet's indecision has taken. As Hamlet himself notes, "What a piece of work is a man! how noble in reason! how infinite in faculty! in form and moving how express and admirable! in action how like an angel! in apprehension how like a god! the beauty of the world, the paragon of animals! And yet, to me, what is this quintessence of dust?" (Act II, Scene 2). This speech highlights the fragility and transience of human life, and suggests that the pursuit of revenge ultimately leads to destruction.
Furthermore, the tragic ending also emphasizes the play's themes of deception and betrayal. The final scene reveals the extent to which characters have been lying to and manipulating one another throughout the play, ultimately leading to their own demise. For example, Claudius's plot to have Hamlet killed ends up backfiring, resulting in the deaths of both Hamlet and himself.
In conclusion, Shakespeare's choice to end Hamlet with a tragic ending contributes to the play's themes of mortality, revenge, and the consequences of inaction. The play serves as a cautionary tale about the dangers of indecision and the pursuit of revenge, while also emphasizing the fragility of life and the destructive power of deception and betrayal.