Why use scripts instead of programs? The explanation can be found on their site:
You may ask, why write scripts instead of real Android applications? Admittedly, Android's development environment makes life pretty easy, but you're tied to a computer to do your work. ASE lets you develop on the device itself using high-level scripting languages to try out your idea now, in the situation where you need it, quickly.
On the website where you can download the ASE you'll find some example scripts as well: One example script mutes the ringer of your Android phone when the phone is face down.