"The Mote in God's Eye"
The first two are science fiction books that take place in the future. The third is a movie that take place in a distant galaxy in the past. All three feature emperors ruling over vast regions of outer space.
A reoccurring theme in sci-fi is technology moving forward while society moves backwards. So you'll have post apocalyptic movies where everyone rides around in hovercrafts but nobody exhibits any manners or personal hygiene. In the examples I've cited above, it is taken to its logical extreme: People can fly faster than the speed of light but can't choose their own leaders. It's as if while all the smart people were working on faster than light travel, the dumb people banded together and made one of themselves king.
I would think that, no matter how evil or powerful you are, referring to oneself as "emperor" is a bad PR move. It pretty much spells out your intentions in advance, which is what most successful politicians try to avoid. I could imagine someone like Palpatine becoming neighborhood association president, but he simply wouldn't be able to influence more than a 1000 followers in real life. And most of them would be trying to rub him out so they could take his place, so you could see how that model breaks down rather quickly.
"Dune" "TMIGE" and "Star Wars" are classics. The writers were likely trying to imagine a society different from that with what the audience would be familiar. I hope that future writers try to imagine something that has not existed yet, rather than something obsolete.