The European Central Bank has made significant progress on matters of transparency and good governance. This was noted by the European Ombudsman, who commended the ECB for adopting the “Guiding principles for external communication by members of the Executive Board” and “encourage[d] it to lead the field on all aspects of good governance”.
You must have rules. You cannot rely too naively on the spontaneous functioning of markets. Central banks were created when it became apparent that it was necessary from time to time to exert some discipline in the market.