Here's a list of topics in which knowledge of ejection velocities from impact craters could be highly relevant. I won't go into detail; they're included here just to give you an idea as to how important knowledge of ejection velocities from craters can be. Origin of cosmic-dust particles Lifetimes of the rings of Saturn, Jupiter, etc. Thickness of ejecta at the Apollo sites Rates of erosion of planetary features by secondary impacts Horizontal mixing of material across a planet's surface "Flow" of material in the target before it's ejected Time required to form a crater of a given size Rates of erosion of asteroids Transport of meteorites from the asteroid belt Rate of loss of material from airless bodies Spread of wildfires from large impacts on Earth Origin of tektites Spectral modification of asteroidal surfaces Origin of asteroidal satellites Origin of planetary rings I gave myself two minutes to come up with this list, and they're up. I think you get the idea…