I think this article argues a bit too strong. I personally prefer Leonore Skenazy's blog[1], which argues for the same idea, but with simpler arguments.

As a side note, Skenazy was called "World's worst mom" for allowing her son to ride the subway by himself[2].

[1] http://www.freerangekids.com/

[2] http://theweek.com/article/index/96342/the-last-word-advice-...