If you are trying to decide among a few people to fill a position, hire the better writer. It doesn't matter if that person is a marketer, salesperson, designer, programmer or whatever; their writing skills will pay off.
Why?That's because being a good writer is about more than writing. Clear writing is a sign of clear thinking. Great writers know how to communicate. They make things easy to understand. They can put themselves in someone else's shoes. They know what to omit. And those are qualities you want in any condition.
Writing is making a comeback in our society. Look at how much people email and text message now rather than talk on the phone. Look at how much communication happens via instant messaging and blogging. Writing is today's currency for good ideas.
Source -- Rework, by Jason Fried and David Heinemeier Hansson