Bump and run is a much safer shot because its easier to control and predict. The problem with a flop shot is that its easy to blade the ball and hit a low, line drive that goes 30 yards over the green and because its difficult to predict where it will stop because you never know just how much spin you are going to get.
The flop is a great shot if you have the skill to pull it off but its also a high risk shot that most pros would advise you to use only when you have no other option.
The opposite is often far more true for people that know how to hit a simple pitch shot.
More often distance control becomes more difficult with a bump and run. A 2 MPH error on a club moving 10 MPH is a larger error than a 5 MPH error on a club moving 50 MPH.
"Flop" may shift the odds somewhat depending on how one defines "flop" but it doesn't have to. I can hit a "flop" shot from a relatively square setup.