I don’t know whether a “significant number of American voters seem to believe that the unemployed don’t really want jobs because they would prefer to live off unemployment insurance or other social benefits.” But I do know that that’s how Casey Mulligan and a significant number of neoclassical economists see the world.
Nancy Folbre clearly explains the appeal of the neoclassical argument:
It absolves believers of any responsibility for other people’s hardships. It lends credence to the assertion that the labor market would work just fine if it weren’t jammed up by a social safety net. It lays the blame for persistent unemployment squarely on President Obama, who has urged extensions of unemployment benefits and other forms of public assistance.
She also demonstrates that the neoclassical view doesn’t explain but a tiny percentage of the existing unemployment rate.
So, let me ask the relevant question: if neoclassical economists are so hell bent on identifying and blaming those responsible for idleness, why don’t they search for and pin the blame not on workers but on the idleness of corporate profits?

Recently, I’ve been writing about this.
The voluntary unemployment myth has other advantages that Folbre did not mention. It provides a convenient target for the public’s contempt: it’s not that bosses aren’t hiring because they don’t see it profitable; it’s these people who are worthless.
And it offers a subtle warning to those still in employment: you can be next, so you better behave.