This nice quote from Milton Friedman (in the context of overhauling the Federal Reserve, as it happens) was recently quoted in the context of health care reform, specifically in support of considering single-payer systems. I’d add democratic reforms such as proportional representation to the list.
… it is worth discussing radical changes, not in the expectation that they will be adopted promptly but for two other reasons. One is to construct an ideal goal, so that incremental changes can be judged by whether they move the institutional structure toward or away from that ideal. The other reason is very different. It is so that if a crisis requiring or facilitating radical change does arise, alternatives will be available that have been carefully developed and fully explored.