happen offstage, or do you think they should be included in the action of the play? Explain.
I agree with auntlori--I as a viewer do not need to see every gory moment. The importance of King Duncan's murder is not the murder itself, but the fact that Macbeth has been driven to commit the murder. The emphasis of the play should remain here, otherwise the actual murder scene might be a distraction from what is really important.
If someone were to make Macbeth into a modern movie (one of the few which has not been done particularly well in today's world), you can bet all the bloody and gory scenes would be show. The constrictions of Shakespeare's stage--such as the one mentioned above, as well as the small size of the stage and the use of natural lighting which made it difficult to hide anything or do any theatrical "tricks"--made it necessary to keep many of them offstage. Aside from that, I think it would detract from the reactions and consequences. We don't need to see Macbeth kill Duncan, or his two guards, to see the effects of his guilt. In fact, when all we see is the consequences of this action, we're not distracted by the believability of the murder. I like not seeing every bloody moment on stage, and I think it's stronger for the dramatic purposes of this play and its themes.
Shakespeare's play, Macbeth, virtually begins with the lines "fair is foul and foul is fair," and this motif threads through the entire play. So, since nothing is what it seems, with the actions of Macbeth in a rather nebulous state, the reader is not certain whether Macbeth begins the play as a rather kind man and changes, or whether the predilection for violence is part of his nature.
And, in considering his murders, Macbeth seems more concerned with the disadvantages to himself, and the dangers contained within such actions: "maybe destiny will make me a king myself"; "I'll go to hell." So, the acts themselves are not as important to Macbeth's deterioration as the thoughts about the acts.
Another reason that the murders often take place off-stage is the fact that there were no between-act curtains, a time in which the buried bodies could be removed.