DJ Holloway at 2012-06-08 17:15:10:
I think having a strong theme is a quality (one of many, including character development, dynamic set pieces, powerful third act, dialog) that starts to separate "good" scripts from "great" scripts.
The way I finally understood loglines, as part of this application process, is that a good hook for a story is one that, regardless of effective characters, specific stars, or witty dialog - is still an effective story concept. Interesting to people.
But just because it's a good idea doesn't make it a good script. That's where that other stuff comes in. The execution is what, then, makes it actually sell-able or a strong movie.