Should Artists Work for Free?

The Twitter account @forexposure_txt is dedicated to documenting requests for artists and creatives to work for free. But should artists work for free?
Todd Stone September Skyline

Art and the Wake of 9/11

Art after the 9/11 attacks

The Prose and Pedagogy of “Weird Al” Yankovic  

The pedagogy in the music of "Weird Al" Yankovic