A comment history would be very helpful for the designer. A client might accidentally delete feedback and for the designer to have the capability to view any and all feedback (resolved/ deleted) would be helpful. That way it can be easily retrieved and the client will not have to worry about having to make those comments all over again. It would be a good safety, "backup" feature.
As we haven’t seen a response to our question in three months, I’m marking it as inactive. Please do feel free to file it again if you still want this feature!