They don’t do anything with space that can’t be done just set on one planet with multiple environments and people. Those planets might as well be countries and continents.
They don’t do much with different bizarre alien cultures and environments. I mean, they do, but only in the movies everyone hates. They hardly do anything with the sci-fi components. And the message of the franchise is “Faith>science”.
Look, in my opinion, Star Wars is bad sci-fi. And it should have just done a fantasy story if it wasn’t gonna go all the way with it.