Dyson Spheres: Hoping to Be Surprised
In trying to understand hypothetical alien cultures, we're assuming we can extrapolate forward from our own technology to what we would do if we had the necessary tools. Thus Dyson's sphere, maybe 150 million kilometers in radius, a meters-thick shell rotating around its star. We can see this as a desirable outcome, so we assume aliens would as well. But would they? Perhaps a Type II society would have made breakthroughs in energy management that would render a Dyson sphere a historical curiosity, like some early 19th Century idea of a flying machine powered by flapping wings and a steam engine.
No, I can't imagine what those breakthroughs would be, but then, that's the point. How accurate can we be about predicting what science will find down the road?