[Stormfalcon]

Well it's a lot harder to reach an audience with rock music because most rock music fits into a certain time-frame where it'll be appreciated more than any other time-frame. To add to that, there is a higher chance that are part of the audience won't like the kind of rock music chosen for the movie. The kind of music that was chosen for the animated Transformers movie was really a one in a million thing that could only be done at that time in the 80s. Fast forward to 2007 and it's pretty much impossible to achieve that kind of thing again.

Orchestrated, compared to rock music has a more timeless quality to it. It sounds traditional yet can have the force and ferocity to match the action and enhance the movie pretty damn well. I find that most of the time when people are watching a movie, they don't even realise they're listening to an orchestrated piece cause it just works so well with the action.

That timeless quality explains why the soundtracks for movies like Star Wars, Jaws, Close Encounters of the Third Kind, Independence Day, and Back To The Future still sound as good today as they did when they came out.

Hell, some orchestrated movie themes become so popular that when you hear the first few notes of the songs, you are instantly able to recognize which movies they are from. For example, when you hear:

"dun...dun,dun...dun dun, dun dun."

You get that creepy, eerie sensation, "there's something in the water".
That's when you say, "Hey, that song is from the movie Jaws."