short version: as development progresses, the efficiency of workforce in all fields get increased. at some point you need less people than you have to cover the need of all people. The amount of people that is taken care for without themselves having to put in energy suddenly is labelled "useless" or "leeching" or whatever. Which would only be true if there was less workforce created than necessary.
Seriously... I mean look at all the products the world really doesnt need: like cosmetics products that just have ZERO effect. Those are artificially created needs and they are unhealthy for our resources, our environment, our mind and well, uh, our health.
I disagree there. Workforce efficiency definitely increases with time and better tools, but that doesn't mean that you get to set some ceiling of "needs" and declare that everyone's needs are met. Everyone's "needs" were mostly met in hunter-gatherer societies, but that didn't mean that the development of specialized labor to allow some people to stop hunting and gathering to do art and music was a bad thing, or a waste.
Think about how difficult it would be for us to maintain everyone at a standard of living equivalent to, say, a medieval peasant. Two meager meals a day and a hut to live in. Not very hard, we could probably keep everyone there with minimal effort. But we want better stuff, we want fancy things like electricity, color TVs, computers, cars, fresh food, clean water, and so on. Use the increased workforce efficiency to produce more goods to increase overall quality of life, and if that means cosmetics then so be it.
I will agree that I'm annoyed by the focus on increasing the maximum quality of life rather than raising the minimum quality of life, but I suspect that that's a function of the economic culture that we've built up since the 1850's or so. There would also likely have to be a dramatic increase in education and retraining, another bit that American culture seems generally opposed to. But those are cultural issues, and you won't solve them without addressing them as such. Particularly not by allowing the people who don't have useful skills to sit around and not do anything.