I love the idea of expanding areas to flesh out a living town/town economy and increase immersion.
I don't really love the idea of changing the prices of things.
I think if any tinkering were to be done it would be either only -
Decreasing the value of paintings. You're right, what use do they have for a painting?
Decreasing the amount of gold each vendor has. It makes sense that prisoners would only trade in goods anyways.
But increasing the value of food or medicine etc. is, in my opinion, not worth it and doesn't really add anything great to the game.