I think the problem is with demands for review quality and they are hard to post.
Not everybody wants to start in depth analysis if they just liked that story

I think comment box should be at the end of each story and anyone unregistered should be allowed to post comments.
That way is used on some other sites and it gives perfect results.

Another problem is that if you do not expect reply there is no pleasure to write any comments either.
most of stories are quite old and not clear if their authors still exist or read anything.
It would be nice to have some indicator when story author checked comments last time and maybe if he is working on other stories.

It must be not one way monologue, but live conversation between author and readers.