When you listen to the Wilhelm scream over and over in a short amount of time, your brain is able to focus on that sound exclusively and you are able to pick it out of any random movie without hesitation. At least that’s what happened to me about five or six years ago when I watched this video several times over: http://www.youtube.com/watch?v=cdbYsoEasio
The problem is, it’s overused at this point. It started out as a sound engineers in-joke and now everybody knows about it. The TV show The Middleman had one in every episode. Maybe it’s time to retire it and move on.
I agree. Whenever I hear it I’m taken out of the movie and think about the Wilhelm scream instead of the movie. It’s particularly annoying when I hear it in a movie theater where I paid $10+ to see the film.