There was a short time in the UK where people tried selling computer games/software from the shops that also sold boxed software, copying 3.5" disks and printing off covers. I suspect the problem was/is twofold - real companies who own IP are still uptight about letting others 'make' their product (the games were more like PD/shareware titles), and the technology setup is still just on the edge of being economically feasible (local storage for a decent range of titles or network capacity to transfer them fast enough)