100+ years later, we're still not there. Why?

In his piece, Mill argues that there is a stationary state that will inevitably be attained by modern society, when the standards of living remain unchanged. This concept is reminiscent of the ecosystem/scientific idea of equilibrium - an ecosystem will continue to change until it reaches a point of stasis where the distribution of resources is sustainable. Our society, despite his prediction made in the late 1800s, has still not yet accepted that stationary state. Our lives remain a constant struggle, I think, because of the combination of economic valuation and capitalist economic system. Our economic structure reinforces the concept of comparative advantage: that having more of something than our neighbor offers us benefit that we deprive from that neighbor. This motivates us to continue to relentlessly pursue more - we must always be chasing the accumulation of capital, which is itself an arbitrary and constructed object.
We cannot continue to obey the commands of comparative advantage and accumulation. To do so is to delay the inevitable achievement of stasis, jeopardizing the environment and human well-being.
I think Sagoff can use Mill's concept to further explain why somethings are - and should remain- outside the control of the market, owing to their super-economic value (i.e. have moral or aesthetic value beyond that for which we are willing to pay.) The economic valuation of things, exemplified by the application of cost-benefit analysis and the commodification of the environment or worker safety, is a driving force in our refusal to accept a stationary state.