What's the point of knowledge? Sure, knowing stuff can get you good grades, but after you're out of school, what real use is most of what you've learned? After all, knowing the parts of a cell doesn't help you much unless you're a scientist, and being able to recite poetry from memory is a neat party trick but not much more. If that's the case, why bother to learn anything? Arcadia says that nope, most knowledge doesn't matter in the grand scheme of things...but that in itself isn't enough reason not be interested in the world, because it's the only one we've got.
Arcadia shows us a bona fide scientist (Valentine), but no real poets (Chater doesn't count). By keeping poets offstage while showing the struggles Valentine faces in his analysis, Arcadia suggests that good poetry is the product of genius while good science results from hard work.
In using the language of art to explain scientific concepts, Arcadia suggests that art is immediately understandable in a way that science is not.