In some ways, however, the deaths are of Romeo and Juliet and Macbeth are caused by some of the same flaws. As the second post said, R and J are victims of their own impulsive behaviors. In the prologue to Act II (not included in every publication of the play), Shakespeare calls attention to the emotional impetuousness of the main characters: Now Romeo is beloved and loves again, Alike betwitchèd by the charm of looks. Poor Romeo! The Chorus just told him he is shallow! It goes on to say that passion lends them power. Later in the act, the Friar will wisely tell Romeo "they stumble that run fast." Shakespeare makes it clear that these characters are acting too rashly and quickly.
Macbeth does the same. Although he spends time debating the murder of Duncan, once that is done, he acts with too much speed. He kills the guards without a moment's thought, plots the death of Banquo without consultation, and rushes off to consult the witches again, desparate to avoid any danger of his power. At no time does he stop to consider how best to keep and grow his power - he just acts out in fear. Lady Macbeth tries to engage him in a discussion about Banquo, and urges him to leave things alone. Macbeth tells her, "be innocent of the knowledge." In other words, he brushes her off and is determined to act quickly and emotinally.
The deaths of Romeo and Juliet are tragic, they are innocent victims of miscommunication, feuding families and a plot that goes haywire. Their deaths are sacrificial in the sense that they are a force of good and with their tragic deaths, they heal the evil that has kept their two families apart. So they create a positive outcome with their deaths. Even though it is tragic, there is triumph at the end. Good is the result of the deaths of Romeo and Juliet.
Macbeth's death along with his wife, who are forces of evil, must die so that good can be restored to nature and Scotland. Their deaths are not sad, but necessary, they are evil characters and therefore, we don't mourn their passing like we do the untimely deaths of Romeo and Juliet.
Although both plays are tragedies in the Shakespearean tradition, the deaths in each play serve different purposes.
I have to add that the deaths of Romeo and Juliet can also be compared and contrasted with the deaths of Pyramus and Thisbe in A Midsummer Night's Dream (the play within a play). The artisans in Midsummer perform the tragedy of Pyramus and Thisbe for Theseus and Hippolyta (and the 4 young lovers) after their wedding. In this play within a play, Pyramus and Thisbe are similar to Romeo and Juliet because both sets of lovers are kept apart by their families. Pyramus and Thisbe must resort to talking through a chink in a large wall at night when they sneak away from their homes. Pyramus comes upon Thisbe one night and believes she is dead after coming across a bloody piece of clothing; however, she has only been frightened, not killed. Pyramus, thinking she is dead, kills himself. Thisbe then stumbles across Pyramus' body and subsequently kills herself so they can be together in death, just as Romeo and Juliet did.
Romeo and Juliet die because both act impulsively. Romeo's immediate response to the news that Juliet so-called death from Balthasar is to kill himself. He does not go to the Friar to learn what happened; he merely reacts. Juliet does the same. When she sees Romeo dead, she immediately kills herself. This reactionary behavior is consistent throughout the play and leads to their downfall.
On the other hand, Macbeth's downfall is his growing ambition and power-lust. He starts the play as a loyal general, but once he is convinced that killing King Duncan is the only way to get what he wants, he leaves loyalty behind. His greed for the throne and willingness to destroy anyone who gets in his way leads him to believe the witches' second set of predictions for him, making him arrogant and cocky. He is told that "no man of woman born can harm Macbeth" and that no harm will come to him unless Birnam Wood were to come to Dunsinane. In his mind, since EVERY man is born from woman and there's no way the woods could come up to the castle, then he was safe no matter what tactics he took. This arrogance led to his downfall and eventual death.
The deaths of Shakespearen tragic heroes is usually because of a tragic flaw in their personal character. By examining the behavior and reactions to the conflicts throughout the tragedies, you will be able to discover just what it is about each that leads to death.