Having something important to say and knowing how to say it well are two completely different things. It is not easy to achieve both at the same time. At this current moment, I am not doing either with any particular amount of skill. But that is what makes a written work truly great and appealing to the widest population possible.
Twilight series. A good story, but not written with very much attention to literary devices that attract readers.
Poetry. It may be absolutely beautiful language, but if no one understands what is being written about, it will not be successful.
Therefore, when I write the book that will change the world, I need to make sure that it is a compelling story, but written well, with so much attention to detail and so many subtle literary devices that all non-English majors will be tricked into thinking that it's plain language. Then, I will have struck the perfect formula for winning over the masses.
But if I can't learn how to do it in a simple essay for a literature class, I have a long way to go before I can do it for the world.