These - often statutory - restrictions on the central bank are imposed to ensure credibility. History shows examples of successful currency boards, e.g. Estonia, and total failures, e.g. the currency board in Argentina. A country opting for a currency board has to defend its own currency.
In my opinion, we need to deal with them with some urgency. First, there remain significant imbalances in global savings and investment, and all of us should be doing what we can to maximize the chances that these imbalances can be unwound in a smooth and gradual way. By and large, this means promoting policies that allow market-based adjustments to take place.