Too few things slot on showcase wall item

The Ingenius Ingvar Creator's Showcase from Businessess and hobbies has extremely limited use. Only about a handful of item types can actually be sold on there. 

Why can we not use it to sell all wall-hanging-collectibles? Posters, tassles, magic broomsticks, feathers... I really think all wall-hanging items should be able to slot there. Whats with only some paintings and wall art and not others? How is this decided? Places so much unneccisary limitation on you as a player