"...only entertained if a guy lights up the radar gun?"
I really love baseball. If I am going to spend my money to go to a professional game I want to see more than a high school quality pitcher.
To address your point of being "effective", I once talked with a great hitter and he was saying that he never could understand why the top recruits and prospects were always guys who had 90mph+ stuff. Because it was harder to hit the real slow pitching.
So I am not arguing about whether it is effective or not. Because it could be at times. But, I am not spending my money to go watch a big league game with a high school quality pitcher.