It used to be that if you wanted to add audio or video to a sidebar widget you needed a plugin. Or if you wanted to add an image you needed to upload the image and write the img tag into a text widget. Or if you wanted a text widget with formatting you had to write in the HTML tags yourself.
The new Video, Audio, Image and Text widgets clear all of that up and make it really easy. I don’t know why they didn’t think of it sooner!