I see what you're saying Acd, but I think your post has more to do with the role of currency in trading goods (which is a whole other argument). What i'm getting at is more the role is work itself from a society standpoint. Currency is abstract and relative; that is, doing the same job pays differently depending on where you live, your experience, your gender, and other factors. Payment for services or goods is often negotiable. What isn't negotiable is the need for the work to be done.
To give you an idea of what I mean, consider the rise of machines replacing human labourers in production. When it is cheaper for a business to build and automate machines than pay labor wages, the "jobs" become obsolete because there is no demand for skilled workers. We see this all the time. Eventually, the high paying jobs will be narrowed down into exclusively fields that operate the machines (which is happening now ie; Healthcare and Technology) Kind of the opposite of what happened during the industrial revolution. What will happen when machines are so advanced, they can replace every menial job in existence?
But this isn't about machines replacing workers. I think that work fullfills a "purpose" more than anything else. Find a skill that keeps the money flowing or benefits a company, and earn a personal reward. Ideally, I think that societies should be working long-term toward eliminating work as a requirement to live, that one day most jobs will be automatically run, and everyone will receive a stipend to live on. Unfortunately, this conflicts with most positions of power, which rely on exploitation of lower paid workers. Essentially, its still a jungle out there, but the predators are wearing suits