The main difference between the original trilogy and the spinoffs isn't the setting but when they were created and by whom.

The original trilogy wasn't social commentary. It wasn't complex or philosophical. They were just fun 70s/80s action movies, like Indiana Jones but in space. The evil guys were evil, the good guys were good. No need for any kind of deep or complex stuff. Good guys shoot bad guys and are good because of that, no matter what else they are doing.

The modern spinoffs were created in the last ten years in a very politically charged environment. Escapism wasn't the point any more, instead you see a lot more social commentary. There are actually imperial characters that have something like a character arc, like e.g. Syril Karn or Dedra Meero. We see a lot more of what goes on behind the scenes in the Empire. We see people who are thinking they are doing something good, following orders and causing mayham instead (e.g. Syril being manipulated into starting the rebellion on Ghorman).

There's a lot more depth there, but I still don't see them portraying the Empire in any positive light. I do see them portraying the rebellion (or at least parts of it) in a very negative light too, though, showing that even the "good" guys aren't exactly good. Like e.g. Saw Gerrera, who is a plain terrorist, or Luthen Rael who commits all sorts of atrocities for the greater good. Luthen himself states multiple times that he is not a good person and that he has no place in the society that he tries to create.