“John Browning preferred hammerless or internal hammer pistols. He put hammers on two of his most famous designs because that is what was asked for.”
The cavalry way, when the 1911 was introduced was hammer down on a loaded chamber. Cocked and locked as a constant carry mode is pretty much a post WWII method.
Cocked and locked on a 1911 is pretty safe since two safeties must be engaged to fire the hammer down, the grip safety and the lever safety locking the slide and hammer. Many hand weapons now have hammer safeties built in, which require the trigger to be all the way back to remove a hammer block to allow the hammer to engage the firing pin/sear combination.