It appears to me that this is the place WP developers are trying to get WP plugin developers to present their plugins from. Given the fact that plugin developers often don't have enough time to even provide detailed documentation for their plugins, why would the majority of them take the time to sign up at the repository?
It is important that there be a central place to download plugins for end-users. Lord knows there are a gazillion places out there now! However, it is also equally important that it be an easy process for plugin developers to submit their work. After all, the work itself is what is important and they don't need to get bogged down with a lot of red tape.
And what of the end-user? Shouldn't s/he have the ability to submit a plugin to the list? Often times, developers create plugins for their own needs and post them on their weblogs for anyone who happens by. They don't want to take the time to add them to a repository.