I think the problem is, when you are running, the window is also scrolling, so the smashing animation is lost in the whole movement of the window itself. I just tried this several time now, and it really isn't obvious that there is a smashing animation at that point. Also, the eye tends to be looking ahead, so unless you expect to run into the wall (which you wouldn't), you aren't actually looking directly at that spot. The sound effect is also just a bump sound, so not really dramatic enough to indicate that something catastrophic (like your head falling off) just happened.