We don't need a 40 hr work week, but we do need better pay and benefits.
The majority of jobs are no longer in factories. In addition, with our technological advances, we do not need 8 hrs/day to get our work done. The work day should be reduced to 30 hrs a week. Not only would this reduce wasted time, it'd increase personal/family time and reduce employee stress, which would increase productivity. Also, the US should require minimum paid leave of 20 days for all full-time employees (and 10 days for part-time.) This would also reduce stress, increase productivity and boost the economy as people have more time to travel and spend their $.
Lastly, minimum wage should be increased to $14-16/hr to at least bring low income pay into the $20Ks. We can't expect people to live off less.