I'm a bit baffled by the default permissions for Authors and Contributors.
For Contributors, would it not make more sense for their posts to be publishable but requiring moderation? This way, an editor or admin won't confuse a contributor's first draft that they are working on with their actual finished post.
For Authors, shouldn't they have the ability to edit reader comments turned off by default? Editing of comments should be the sole responsibility of editors and admins I would think.
Even if these aren't set by default, I would think their should be a way to easily change these permissions. The Roles and Capabilities page does not indicate a way to do this - there is no way to publish for an approval process, and if you can edit posts, then you can also edit comments.