This has bugged me a lot and, IMO, it's a classic sign of a lazy storyteller . . . I'm talking to you Lucas. We've had some great sci-fi tales and across the best of them is the common arch of realism - yay realism!
Mass Effect: I can't remember the dates but it was that far into the future. Humanity discovered some aliens and we got a massive boost to our tech - not just the weapons used in the game - but across the board. ALL our tech. The average human lifespan became 150 years and this is because (in real life) scientific study is balanced unless there's an actual war on.
Dune: A long long series of amazing novels, with many of the sequels taking place decades or centuries apart from each other. And you know what we saw there . . . progression. Things changed, tech advanced. Towards the end of the series people were living over 300 years and they sat down on sentient, dog chair things.
Star Wars: Across like . . . 30 000 years nothing has changed - ever. I think force users used to have a backpack for their lightsabers, and that's pretty much it. We can telelport across galaxies but the average human life span is still less than 100 years? Are you kidding me? Cybernetic limbs, cloning, kolto tanks . . . but none of these things led to humans living a few extra decades? For those who love to play devil's advocate the Emperor's special treatment does not count . . . this should be ordinary, general medicine.
P.S and every planet being either a single giant city, wasteland or having a total of 4 species inhabiting it naturally is also just plain lazy. Aaaaaah, that feels much better XD