Free will. What's so special about it? Why would anyone think that free will could be of such importance or even garner such interest? It's not even something that we'd consider that much - until of course we don't have it any more, and then it becomes one of the most important things our your lives; crucial to our liberation and self-actualization.
What motivates the Dark Side to play out its role, what is evil, and what is the real reason Light and Dark are playing out this duality? Why would those aligning with the Dark Side care enough to want to go to the trouble of seeking to prove that free will, therefore a benevolent Creator and universe, do not exist? What benefit is there for them in that pursuit?