Answer :
The audience would actually watch all of the characters turn to stare at the rocker, which could enhance the mood of the scene
One advantage of watching the scene presented in the question from "Trifles" instead of reading it would be that by being there physically, the audience would be able to watch all of the interactions that the characters make throughout the scene and the rest of the play. When by the end of the scene the stage directions states that all of the characters look at the rocker, if the audience is watching the play they would actually see that action being performed instead of having to read it and visualize it on their minds.