This is not so much about the top makers "making" art knives so much as marketing them to art collectors. The flow and choice of materials of the best makers is as much an artistic exercise as painting, or even it's closest kin, sculpture.
Can you think of something more humble than a clay jar? In the right hands a simple container becomes art and is highly collectable. I don't feel that art collectors shun knives, I feel that they haven't been presented man's oldest tool as an art form.
This would be a grand opportunity for the newly founded Custom Knife Collectors group to put together a marketing plan targeting a diffent market. Man's oldest tool as art.