Unemployment solved: 20-hour work week

While watching yet another presidential candidate promise how he would stimulate the economy to create more jobs, I found myself wondering why nobody is talking about an obvious solution: restricting the supply of labor by cutting the working hours.
 
Given the current productivity levels and 5 billion people of working age on the planet, it does not seem possible to give everyone a 40-hours/week job doing something useful.  There is a precedent for reducing working hours.  We went from 70 or more to 40 a while ago.  We also eliminated child labor.  Was it a coincidence that real wages went up and the middle class got created since then? 

Why is 20-hour work week a bad idea, or a good one?

>>35
Everything more expensive sounds truly awful.  Does that mean I could not afford food and shelter, or does that mean I would only replace my cell phone once every three years instead of every 18 months?

If this is a shitty idea, what do you propose instead?  Status quo is clearly unacceptable to a growing number of people all over the world.  Status quo has gotten us to the point where we need to keep killing a dozen of “terrorists” every day to remain “safe”, and “trouble-makers” are rioting in our streets instead of looking for porn on 4chan.
 
Who will you want to keep your ass “safe” when the “trouble-makers” of the world come knocking on your door, armed with some nasty weapons?  Will you vote for someone like Hitler or maybe somebody like Stalin or Mao?  And will you still be worried about the price of your next flat screen TV?  I am sure the status quo looked pretty good to the Russian Czar back in 1917.  He would have called himself a Conservative, until the “trouble-makers” knocked on his door.

Why do you think someone like Warren Buffett wants to pay more taxes?  He gets this.  Do you?!