I have a friend who is charming, charismatic, a dynamic story-teller, great sense of humor -- and a loud talker. I think it's difficult for him to contain all that personality and enthusiasm so something has to give, and that something is usually volume control. When heads start to turn in a restaurant (and unfortunately not because we're so disarmingly attractive), it's usually time for the pointed reminder to "use your indoor voice."
I welcome his enthusiasm and I appreciate the talents of a great story-teller probably more than the next. In fact, the ability to tell a good story is practically mandatory in a friend and really just about anyone I have to spend any significant time around. So why the admonition to shush it then? Because I can't fully concentrate on what he's saying when I'm aware that we're annoying people around us. My attention is now divided between his words and the looks being thrown our way (and in one extreme case, the waiter rapidly bearing down on us).
So what's the point? To effectively get your story heard and your message across, everything needs to align -- the words, the voice, the method of delivery, the audience. When even one of these is off, you've sacrificed the impact of your communications.