Americans are rightfully worried that American children are lagging behind their German/Russian/Japanese coevals in Mathematics and Science education.
At the same time Americans want their children to have a "happy childhood", therefore they protect them from homework just like they protect them from drugs and traffic accidents.
It would seem that "happy adulthood" is more important than "happy childhood", and, since education is crucial to being productive and it is impossible to be happy without being productive, we must encourage homework!
But then, "with much wisdom comes much grief, and he who increases knowledge, increases pain" (Kohelet 1:18), and IQ and education are positively correlated with depression and suicide...