I'm very new to WordPress and am currently working on a new site which is open to all. The problem is, I'll be having a few items that shouldn't be viewed by younger people and will needed a members only section. This isn't a problem. The only problem I thought up is the image area. As of this point there is only one upload area and for members only, this could be a problem since some of the items that I will be uploading, again, shouldn't be viewed by younger people. The problem is, Google and other bots will be indexing all images in the directory.
If you where to add a members option to WordPress's core, you then would be able to add more options such as a new area for images and other items for member access only that in turn would give us more power to control what the bots will be indexing.