REASONS FOR CHANGING THE ENDINGS OF MEASURE FOR MEASURE AND HAMLET. I usually take the traditionalist view of productions of Shakespeare. However, I can understand the point of the changes in the endings of Measure for Measure and Hamlet. As I explained in this post, Measure for Measure explores the tension between mercy and justice. In the ending as written, the Duke as an exercise of mercy pardons Barnardine, who is a murderer. The director, in choosing to have Barnardine kill Isabella, is making a plea that justice should not be entirely forgotten.
As for Hamlet, one view of the play is that Fortinbras is a much more important character than is usually recognized. Fortinbras, in contrast with Hamlet, is a man of action who at the end of the play has avenged his father. In a production where he shoots Horatio, he is asserting his power.