Well he didn’t do a doctor strange. I don’t think it’s more interesting. I think it panders to the portion of the audience that quietly likes those negative traits and probably preps a lot of less than critically thinking readers to be more receptive to those traits. It also doesn’t fit the thematic style of stars which pretty clearly settles into clean camps of good and bad. The emperor served the function of embodying everything that was clearly bad. He was deceitful, sadistic, authoritarian, genocidal, xenophobic, vengeful, and probably much more but I think you get the point. He didn’t serve as a complex character, he served as one of the extremes of the moral landscape that the actual characters navigated. At arguably the highest climax of the story Vader is only redeemed because he rejects the symbol of evil. Adding a secret motive that makes excuses for his blood soaked accumulation of power mucks up the story framing and didn’t even come close to accounting for the vast array of just plain evil traits he exhibits. He didn’t cackle gleefully while making a father and son fight to the death because it was a grim but necessary step to protect the galaxy, he did it because he is the personification of evil in the story.

I do think that there is a place for complex villains. They are generally much more interesting but they also require a skilled writer and importantly an audience that can understand that, complexity aside, they are still the villain. We can look at the alarming percent of the Breaking Bad/Rick and Morty/Punisher fan bases that don’t get that to see the perils of that type of story telling reaching the wrong people. The emperor was not one of those complex characters and trying to retcon that in was at best clumsy and foolish.