The main reason for this major change is that even in the presence of information-sharing provisions of treaties, Switzerland refused to provide any information

The main reason for this major change is that even in the presence of information-sharing provisions of treaties, Switzerland refused to provide any information on most account holders that were evading US (or other countries') taxes, on the rationale that evading non-Swiss tax was not a criminal offense in Switzerland. Cooperation was virtually nil, especially in the tax arena. Depending on the scope of the changes, this could be huge news.