WordPress is a very comprehensive platform. Writers sites like www,authorsden.com have introduced blogs. Is it not possible for you to do the reverse and charge for it the way authorsen does?
After all what does a writer or a poet want? He wants all his works under one roof(and categorized) and a communitiy with which he can connect. You just have to duplicate the software with a few changes here and there and put it as an add on. Currently too all the articles can be introduced with blogs but one would also like to mention the date on which it was written unlike the default setting of blogs.
http://www.authorsden.com too is a wonderful website but for them to create a platform like you would be like the tail wagging the dog. For you it would be easier. Just a suggestion.