I think it depends partially on skill and partially on intent. I would consider the work I do very much a craft. The model is effectively a 3d paint by numbers that I attempt to not botch. There's a skill level that I think supersedes this and becomes an actual work of art. At a certain point the paint job transcends the mini to become a separate piece (Miniac's chaos bust comes to mind -- the paintjob was so much more than simply filling in blanks on a bust). There's also a level of intent when you look at some of the more involved dioramas that are providing a scene that clearly more than "Armor is red, rivets are silver".
The inverse could be said about traditional art. While a painted canvas in a gallery is clearly a work of art, is a line assembled oil painted landscape a craft?
The inverse could be said about traditional art. While a painted canvas in a gallery is clearly a work of art, is a line assembled oil painted landscape a craft?