There are two issues with doing artifacts for the calendars, because artifacts by design are an item that synergise with one of the classes to change it in some way, and aside from dragonlord, each class only gets ONE artifact(shadow base gets the shadowheart bracer, base gets the cloak scrap, SW and eventualy MSW get's baltael's aventail). So the issues lie in what kind of artifact the calendar would give, and what class it would go to.
Issue 1.) If it's an artifact for a calendar class, it will be useless for anyone who hasn't bought said calendar class, thus giving that person less of an incentive to buy said calendar. This means that a year where a calendar class gets an artifact from a calendar, the number of DF players who buy the calendar will theoretically DECREASE, as only the people who have said class would have any incentive to buy the calendar. this would also give AE less incentive to make something for DF next calendar.
Issue 2.) If it's NOT for a calendar class, this leads to two more problems. Which class would get it, and the fact that that class' artifact has now been used up on a rare that more people than not can't get. This is an issue because, as a whole, artifacts are a readily available thing for anybody, assuming they have a dragon amulet, and/or dragon coins. even artifacts for classes that we can't get anymore, like the shadow base class.
It has already been stated that calendar classes will NOT be getting re-releases of any kind. We had an entire 4-and-a-half thread long argument over whether or not they should, and higher ups said no, ending it there.