I'm wary of what people will start doing to their kids once this passes through the telephone game of science reporting -> MSM -> well-meaning parents following 'cutting-edge' parenting techniques.
My friend the professional immunology researcher often expresses her disbelief at how parents try to protect their kids from dirt. Also, Nature isn't really the MSM.
I know - the next step is CNN.com (or whatever) "Scientists say you should keep your kids as dirty as possible" then you have, I don't know, parents smearing pig shit over babies or something. You get the idea.