Good comments, and I agree about using the right tool for the right job, but here's a possible reason to not ditch the idea out-of-hand. The client. I was tasked with putting together a site for my church. Our users are not very tech-smart. I went with WP because I can get the most functionality with a single interface that they can actually operate. It reduced the learning curve and eases the change management. An WP-integrated PM capability would be easier for the users and therefore less maintenance on my part. It is not what WP was meant to do, but ease of integration and user-ability matters. Necessity is a mother.