The core issue is freedom. Americans are punch-drunk on freedoms. We demand the right to do whatever we want without anyone telling us what to do. It's our birthright and what our forefathers and hero-soldiers (someone else) fought and died for.
How can you force someone to work hard, be productive and escape poverty in a free society? We're too compassionate to let them starve, so we prop them up with social programs, while essentially demanding nothing from them in return. It's not truly painful to be at the bottom, at least not in a first world country like America.
It's kind of like evolution without the survival of the fittest part. Our social programs ensure even the most unfit get free room and board, so there is no real incentive for them to evolve into more productive members of society if they choose not to.
That's American Freedom for you. If you want to be free to excel, how do you tell others they can't do the bare minimum? The world needs ditch diggers too.
EDIT: And stop with this geeky fantasy that robots or automation is going to eliminate all need for manual labor while simultaneously proving a world of cheap, quality goods. No amount of automation is going to provide the world with $.25 Big Macs or $200 flying cars.