Retroactive OA to an award-winning article

The Journal of Labor Economics is providing retroactive OA to an award-winning paper originally published in January 2004:

Pascal Courty and Gerald Marschke, An Empirical Investigation of Gaming Responses to Explicit Performance Incentives.

From the journal's announcement:

The Journal of Labor Economics awarded Pascal Courty (European University Institute) and Gerald Marschke (SUNY ­ Albany) the H. Gregg Lewis Prize for their article....Awarded biennially in even-numbered years, the Lewis Prize honors the best paper published in the Journal in the last two years....In honor of Courty and Marschke's award-winning work, the University of Chicago Press has temporarily lifted all access restrictions to the article....

Comment. It's an excellent idea to provide retroactive OA to articles when they, or their authors, win subsequent awards or recognition. But why not make it permanent OA? Does the press really think it will gain more from toll access to an old but respected article than it will gain from OA that draws new readers, impact, and citations? In a forthcoming article, I argue for systematically providing permanent OA to past research articles, starting with the most important.