The problem with unlicensed spectrum is the same as for anarchist utopia. There's essentially a single rule (maximum power limit, but even that is poorly enforced), but lots of anti-social behaviors are possible even abiding by that rule.
You might find the history of unlicensed spectrum interesting http://mises.org/daily/1662 TLDR: in the 1920s spectrum was treated as a homesteadable property right, which you could use to stop others interfering with you and could trade.
There has been some very good work in how to add more structure and rules to unlicensed while keeping its good qualities: http://ir.lawnet.fordham.edu/cgi/viewcontent.cgi?article=411... http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=154265...