BOAC:
If, as may appear to be the case, your "More than a few crews have forgotten to set the flaps for takeoff, then when the warning sounds off with application of takeoff power the crew wakes up and selects takeoff flaps and presses on with the takeoff." is correct, it appears that training and airmanship have failed - I have no other solution - do you? At least, stopping the 'cowboys', even AFTER a "a successful shoot-out" might prevent another from the same?
Because we had two terrible crashes in the U.S. due to this, it is a certainy there were "X" times more that caught it and got away with it. My view is, "thank God for the warning horn" and, further, that should be redundant with today's technology.
No doubt this "cowboy" act is really bad airmanship. But, there are a lot of other acts of poor airmanship that have resulted in flying into the ground or the side of a mountain far too often.
And, there are always shades of grade, such as a lightly loaded 727-100 taking off Day VFR on a long, dry runway, and the captain immediately figures out the problem as takeoff power is applied.