Actually, the old Smiths with the old style hammer block are safer than you may think.
There had to be two internal failures for one to discharge by falling on the hammer. The first line of defense was (and still is) the bump on the top of the rebound slide which automatically cams the hammer back slightly when the trigger is released. A double action revolver with a swing out cylinder has to have a rebounding hammer like this or when you try to open it the firing pin can get stuck in a fired primer. Swing out cylinder Smiths have always had a rebounding hammer for this reason. The very early Smiths had no hammer block at all, completely relying on the bump on the rebound slide to withdraw the hammer.
(Actually, before 1905 there was a different mechanism that did the same thing, but everything made after 1905 has the bump on the rebound slide)
So even without a hammer block, the blow to the hammer would have to be quite stout. Stout enough to either crush the rebound slide, break off the lower portion of the hammer, or break the stud the hammer rotates on. Still, safer than the so called 'safety cock notch' on a Colt SAA, which could snap off it you looked at it crosswise.
I forget what year S&W started installing hammer blocks, but it was quite early, probably the late teens or early twenties. There were two different styles of these early hammer blocks.
This is the first style. The hammer block was a piece of spring steel staked to a slot in the side plate. A spring loaded plunger shoved by the hand pushed the hammer block into the side plate, withdrawing it from between the hammer and the frame.
The second style is what failed in the Navy incident. This one used a ramp on the hand to withdraw the hammer block. Less parts, simpler to make than the first type. It was determined that cosmoline had not been properly cleaned out of the mechanism, and the hammer block became hung up in the retracted position. Still, not only did this need to happen, but something also had to give way with the rebounding system. I seem to recall the hammer stud sheared in that case, but I could be wrong.
Anyway, since it was wartime, and S&W had some pretty big contracts to provide revolvers to the government, they were told to fix it fast. S&W set up some fixtures to drop revolvers onto a concrete floor. I forget how high they were dropping them, maybe belt height or something. They did get some failures.
So the engineers were called in and within a week they came up with the modern style hammer block. The hammer block is a separate part which rides in a slot in the side plate. Much more positive, this one relies on a pin mounted on the rebound slide to withdraw the hammer block. When the trigger is released and the massive spring in the rebound slide shoves it forward, the hammer block is pushed back up between the hammer and the frame. In point of fact, the rebounding feature of the hammer still functions to keep the hammer back, and the hammer never actually touches the hammer block. It is there for added insurance. This is the same style hammer block S&W has been using ever since 1944.
Even with the new MIM parts, they are still using the same basic hammer block design.
The hammer block is still a stamping. The part is stamped first, then twisted to form the tab that goes between the hammer and the frame. The one at the top in this photo is the type used in all the guns made since 1944 with forged parts. The one at the bottom is the type used in the MIM parts guns. For some reason, it is twisted the opposite way.
I still can't figure out why S&W wanted the hammer to block the sights on the Victory Models. I have lots of old Smiths, and I can see the sights on all of them with the hammer down. Maybe Smith thought WWII service men did not need to see the sights for double action shooting.