i notice rpc's in certain locations regularly. but who says the have to stay? however, vanity alone would be a good motivator to keep them there. of course they don't have to stay there though, its just to add more flavor to the scene, and to show these people are important. the character art would be specifically tailored for certain locations, not every place the rpc travels. and again i think 1-3 locations tops.
i don't think more than 3 different rpc's should be visually represented in any one scene, would probably be overkill. but i don't see anything wrong with one of them there. and i don't think any rpc should take priority, to me that's degrading. just pose the rpc in a different spot if more than one is present in the scene. any scene that would be cluttered by the introduction of an rpc, shouldn't have one.
Even the tiniest change to a scene whether it be something as small as an ant in a faraway lighthouse to something large in the foreground alters things, thus making it more interesting.
from what i hear it sounds like the artisan guild is small and other things are probably more pressing. i was just thinking this because the art is a strong part of the game and should be taken advantage of, if possible.