I totally agree with you Jonathan. Storyboards can even help you to identify flaws in the interaction or already give you the chance to simplify/iterate the concept (sometimes in my mind starts too much complicate, given the amount of time I decide to invest). I still have to try Powerpoint/Keynote! I believe Framer.js and Quartz Composer are two interesting choices, also. The whole point is that with After Effects, your interactions are not interactive and this bugs me a bit.