If you do a lot of content creation in Canvas, eventually you're going to want to have a more flexible way of incorporating markup into your text. Markdown is a simple, plain text syntax with direct HTML conversion that makes writing for the web easier. (see Daring Fireball: Markdown for more info)
Incorporating basic markdown support in the text editors in Canvas would simplify the writing process for instructors and students. More complex tools like RMarkdown could be developed in the future to support graphical data representation.