Hilton Lipschitz, on the effects Markdown has had on him as a writer:
The key to Markdown writing is that you focus on the content. Structure, format, look and feel are all secondary. It’s pure distraction-free writing. Which means that you have no choice but to write and think about writing and focus on the content. Which encourages you to become a better writer.
The other issue with writing is that it takes time, but the payoff of Markdown is that you land up spending less time doing it. With no distractions and fast tools, more writing gets done. What you do with the time you gain is up to you, but for me, it means I write even more.
Good complement to the piece I wrote last year for TidBITS on the subject.