A regulatory proposal to raise bank capital has spurred banks to fight back with a populist appeal to consumers, while regulators say more capital is what's needed to save banks from more crises — and help consumers.

The Federal Reserve, historically a secretive and isolated institution, has made a concerted effort to explain itself to and be understood by the public since 2008. But try as it might, the central bank is still viewed by many as an enigma, if not an enemy.