Pretty much this. We forgot how to build domes and make concrete here on Earth... just imagine what the war-torn galaxy far-far away has forgotten.
Also, there's an idea that once technology has advanced to a certain point, it become difficult to do more than make minor improvements upon it. It's sort of like a diminishing return.
I think this is more or less the case. They've reached a technological plateau where the kind of exponential improvements we're experiencing are just not possible.