I think most (though certainly not all) of the people who make movies for a living are passionate about their work. It would be satisfying in the sense of a romantic ideal if that was sufficient to produce quality. It is not. It is merely a prerequisite.

I think you latched onto one of the keys: insecurity. But I wouldn't connect that to choice of subject matter. Any aspect of human endeavour has the potential to be interesting (except NASCAR) whether it's the dead-end kids of Stranger Than Paradise or an "important" person like Lawrence of Arabia, whether it's saving the world in battle or whether it's collecting stamps.

No, I think the insecurity lies in the filmmakers' faith in their own ability to communicate what they want to. Sometimes the problem is in the all-too-conscious attempt to communicate what they want to. Some, like Jim Jarmusch, are confident enough to let the small gestures speak for themselves. Some (I would argue Sam Mendes is one of the best current examples) need back-lighting, swelling music and dreamy-eyed stars gazing significantly off camera every three seconds to make sure he gets across to everybody that "this is really important."

For my money, a good filmmakers gets out of his characters' path and lets the images and sounds stand on their own. Most feel the need to comment on what they are showing, to "take a position" on the material presented. To me, that's almost always the path to mediocrity and the source of so much of the faux-art pretension that plagues "Oscar worthy" films of both today and yesteryear.

-chris