I think it's better that we do not encourage more people to sell their art. If you give someone a feature to use, they'd obviously use it. You'd get loads of kids (about 8-12 years old) opening an art shop, not knowing that they have to scan their art in order to sell it. You'd also get more people saying 'why isn't anyone buying my art?' (since you get a load of people saying the same with their rancher and merchant shops); many of you know that these people are a bit annoying and whiney xD.
Forums are enough. If you wanted to display your art, I suggest you open a deviantart account and maintain a portfolio there. This is a petsite, not an artsite.