Don’t you love when people hijack your thread to make it about their own complaints? 
But so actually LOVE this idea for hardcore in general. It would become a lot more exciting. Maybe even randomize the path and spawn locations of the traveling salesman across Azeroth?
Then if you made it to where players couldn’t mail items between characters it would actually force people to sell their blues and purps as well. More extreme change based on your idea, but I think a lot of it would be a fun change of pace.