interesting one. I like it.
I would ascribe the drive for Mastery as a quality to the Worker in the New World of Work - the "Purpose Agent".
Actually, when trying to come up with a characterization of the Purpose Agent (which is still work in progress) this came up high on my list, too. I'll bookmark that book, thanks!
Do you see mastery a trait of the new world of work itself, or of the worker in the new world of work? I tend towards the latter.