The fact that Shakespeare uses iambic pentameter to guide the rhythm of his words makes the whole play feel like it is moving to the rhythm of a heartbeat, that it has a specific and clear pace. He also makes sure that the events can unfold in the most dramatic timing, rather than just having characters give a lot of information at once. This helps keep the audience interested through the whole play. Also, the rhythm of the lines is almost hypnotic, and can suck the audience in.