Far too amny people simply pick up a pack of 100 grain broadheads without ever stopping to think about their set up. A 125 grain head may very well give them better arrow flight and penetration than a 100 grain head but they got 100 grians on the brain.

Also manufacturers when they come out with a new head the first one they make will be a 100 grain head and many times will be the only weight ofered inthat partivular head. Such as the NAP nitron.

Another thing is that Americans are of the mindset that faster has to be better no matter what.25 grains is not going to make a whoopty bit if difference in trajectory, KE, or momentum. But it could make a noticible differance in the way the arrow actually flys.