I know the "intention" of Quartz Composer was primarily a tool to let
developers test Core Image stuff which they then rewrite into a proper
app.
That's actually not true: Quartz Composer is a OS-level motion graphics
technology which leverages Core Image among other things. To test Core
Image filters in an image processing environment, there's Fun House
designed especially for that.
But I see huge potential in it in Education to teach programming
principles like logo used to be used for, because you can be making
cool
looking stuff in just a couple of hours starting from scratch.
And secondly for "non programmers" who don't want to be programmers
like
Designers, Animators, and VJ's to build motion graphics in a procedural
way with interactivity.