Showing emotion when you speak

Is it good to show emotion when you are speaking to others? Is it career suicide to do this? Or does connect you to your audience more. This is a question I ask in response to Premier Theresa May's resignation speech last week, when for the last few seconds she sobbed. In doing this, did we really see a human side of May that was not visible before? And would this have made a difference to our understanding of her, had we seen this before?