When it comes to Folk Singing, showmanship definitely needs to come to the fore. I can think of many wondeful singers whose voices weren't outstanding, but whose delivery and charisma made their singing wonderful. With instrumentalists, perhaps it not always so important, although when both skills are combined the result is the product rather than the total of them. I remember listening to the late Seamus Ennis playing his pipes and telling his stories. The combination was magic (often in more ways than one).