There are numerous reasons why you would want to add scripting to a program. Remember QuakeC, or UnrealScript? The idea is to add extended functionality to a program that does not require a recompile for each change. It also allows users to extend a program without having to wait for the programmer to (who knows when?) add in the functionality.
Suppose you have a roguelike game that uses scripts for the character stats, items and monsters. A player could tweak the scripts so that instead of a fantasy rl, they could play a sci-fi rl, or whatever they wanted, and it wouldn't require wading through someone else's source code or waiting for a new version that may or may not appear.
I could cite example after example, but the point is, this is something good to have, and to have it already packaged up and ready to use is a real plus. I for one, will find this quite handy.