By default, WordPress’s emails are pretty ugly. No logo, header, or footer or any styling at all really.
Wouldn’t it be nice to add your own branding to it? Make it look like an email someone actually wants to read — instead of looking like a dog’s breakfast of text. Not only that, but you want to make it easy for everyone that reads email on their mobiles, not to have to zoom in and scroll both horizontal and vertical to read!