Seriously, whatever anyone's thoughts of Monkey Island are it all begins with that sound. It just sets the tone, you know exactly what's coming and what everything after this sound entails. This sound represents all of Monkey Island and the amazing cinematic and hilarious experience that ensues after hearing it. And not just Monkey Island, but all the LA adventure games. Or adventure games in general. This sound has made it's mark in history and will never be forgotten. There's no sound like it that can produce the same wave of emotion, memory recall, excitement, and mystery. And it never gets old. Every time I turn the game on and hear that it gets me all hyped up the same way it did when I first played it.
Yes, the main theme is just as important but without this little bit there wouldn't be a main theme.