I believe Toady intends to do this at some point, as several of Threetoe's stories suggest more significant uses for artifacts (trading an artifact as part of an alliance for example). The hard part is Toady tries to script as little of the game as possible, eventually everything in the game will be controlled by some form of AI to make the game almost 100% dynamic. That's the only hitch in this suggestion, either the system has to be automated or Toady will have to write in so many unique artifacts lest the players start to get frustrated when they get their fifteenth singing sword or their twelfth undead-raising pendant that summons dragons when it rains during the full moon ("I HAVE SO MANY CAGED DRAGONS I'M MAKING BURGERS OUT OF THEM!").
That said, the suggestion is brilliant. It's very similar to others suggesting that artifacts should tie in to the magic arc, which is probably where Toady will fully flesh out his ideas on this. The one caveat that I would have to add would be that with how common artifacts currently are dwarves would quickly be buried under a mound of magic artifacts. Either the frequency of moods would have to be lowered substantially or magic artifacts will need to be only a small portion of the total artifacts created.