Why have the producers decided to give dr. griggs a chance to speak lines and interact with the other characters

This is a short-answer forum designed for text specific questions. We cannot discern why producers would choose to change the play nor use dialogue. You might want to look up the specific production this question pertains to, as there have been many different production of this story.

Why have the produces decided to give Dr Griggs a chance to speak lines and interact with the other characters? What purpose does his character serve?