I don't have a problem with having fenders hanging over the side of an anchored vessel. In addition to protecting the topsides against your own dinghy, they protect against other people's dinghies, e.g., someone coming unannounced to say hello, request assistance or possibly even checking to see if you need assistance. I view hanging fenders as the marine equivalent of a front door mat. If I don't see them on an anchored vessel it means no one is aboard or they don't wish to be disturbed.
Now, fenders hanging over the side while under way...that's a whole 'nother issue....