Graeber's research into the phenomenon of bullshit jobs has helped him refine the theory and make some moves towards explaining the phenomenon. He's created a typology of five kinds of bullshit jobs ("duct taper," "goon," "box-ticker," "flunkies," and "taskmasters") and quantified the premium paid for bullshit work, and the discount applied to the wages of people who do non-bullshit work (especially caring work).
Graeber has heard a lot from market-orthodox libertarians who dispute that there can be such a thing as a bullshit job: the market would discipline any firm that wasted money on this sort of thing and it would sink, so by definition, any job that is persistent over time can't be bullshit. It must just be that low-level functionaries can't see the big picture and thus labor in ignorance of the difference their work makes.
Another major contributor has to be the need for the top power brokers in large firms to surround themselves with corporate retainers and aristocrats, who help shore up the top peoples' power and thus their wages -- maybe the market force at work is big salaries for the C-suite, the VPs, the top deans and other administrators whose retinues sprawl beyond all measure.
I like this theory best, because it explains why firms are so quick to cut real jobs (teachers, clerks, waiters, ticket-takers, and other people who interact with the public and do the business of the business) but so reluctant to trim the thick bureaucratic layer surmounting all. From the perspective of a VP hoping to get a raise, the company's profitability (driven by a motivated, valued and robust workforce of non-bullshit workers) is secondary; the primary factor is beating all the other VPs. When asked to make cuts, any VP who erodes his retinue suffers hits to his bonus, while making cuts to useful workers may erode the firm's profitability and cause it eventually crash and burn, but that will be someone else's problem.
Graeber's big point is that a titanic amount of our economy is presently bullshit, and we're working crazy hours to ensure that all the bullshit gets done. If the anthropological pressure to work can be abated and the individual greed of a class of super-rich can be dampened or neutralized, maybe we could realize that 15-hour week Keynes predicted in the 1930s.
Because, as Graeber points out, bullshit jobs -- even ones that leave you free to dick around on the internet or write your novel all day -- make the people who do them miserable.
Bullshit Jobs: A Theory [David Graeber/Simon & Schuster]