A person's wall can make for a nice memorial and I imagine it might help some with the healing process. However, there should be a box that someone can check to mark someone deceased -- if for no other reason than to keep them from popping up in the "suggestions" section.
Several times now, my home page has suggested I "Catch up on Facebook" with a person that is no longer of this world. That's just strange. It might even qualify as disturbing for someone more emotional than myself.