Broken Window nirvana
Basically, I think what we need is for the unsightly half of the world to collapse, so the other half can make a fortune in "stimulus" by rebuilding it. Also, it would be nice if old people died sooner to keep entitlement programs from going bankrupt. To a man with a Keynesian sledgehammer, all the world looks like a gigantic episode of "Extreme Makeover: Home Edition."
Actually, I've always wondered why the specific application of the Broken Windows Fallacy you mentioned does not occur to the "stimulus" crowd. If misfortune creates opportunity for wealth creation through government-directed rebuilding, then why aren't high-crime areas the wealthiest places in America?