Public speaking must be one of the most terrifying things there is. You may have read that public speaking is a bigger fear than death. I don't know if that still holds, but public speaking really does scare people.
Being able to speak effectively is one of the most important skills a person can have. This is even true in science and engineering jobs. In many other types of jobs the ability to make an effective presentation is key to advancement, sales, and a good career.