lack of government laws and regulations around ICOs is the reason for countries banning them... it is a threat to their current financial systems, traditional VC investment fundings..

some will argue that it is to stop scams, ponzi schemes, and people throwing in money into high-tech pump and dump schemes, but that is just the tip of the iceberg.. but let's face it, most governments do not really concern themselves with the financial well-being of their nationals.. esprcially on a mass scale. 

if a government can't control it.. then they ban it.. simple solution in their eyes.