Fixed your link for you.
I wonder if FS was made better in this regard than, say an FPS, where the potential for the player to fiddle with things is somewhat higher. FS has very well recorded vuilt in dialogue (with clear emotional connotations defined by the predictable situations in which they will be triggered) and a relatively linear set of sexp triggered messages, with deviation from this linear path almost always resulting from an event with a single, easily discerned emotional context (like the destruction of a friendly capship when it was supposed to survive).
Of course, it also helps that they got some really professional actors to do the work.