Why not open any post in Live Writer?

Live Writer has a good new feature of opening published posts from the blog, making changes to the same and republishing it. However this retrieval and publishing allows only for the posts that were published from LiveWriter.

I was wondering that why not LiveWriter incorporate a feature to retrieve any post on the blog, make changes locally and publish it back to the blog. That should make it a still more fool-proof and full-fledged blog editing platform.