From a long term perspective, what did he gain from all of the oppression and over centralization of power other than fostering rebellion and instability? Once he was chancellor he could have dialed back the overt machinations continued to exist in the shadows to weaken the Jedi and grow his own power.
Hell, he could have become a sympathetic father figure to the Republic after Order 66 had he just remained as Supreme Chancellor, or even put himself in a position where he could step back and install a puppet successor and maintain the illusion of democracy while controlling the levers of government. Why create an unstable power base for himself when it seemed like he was mainly interested in doing SIth magic stuff in seclusion? Was he just bored?
Honestly, that comes down to philosophy. The Sith are about domination. You gain power through fear and anger. They don’t understand anything else. So they rule based on their philosophy. Also, in Lucas’ vision, creating the Empire was to spread fear through the populace. That fear would reinforce the Dark Side and make the Sith stronger. Every time you have some person get angry and kill another person, or a family scared for their lives, it adds to the Dark Side’s power. It’s a metaphysical reinforcement of Sith ideas that make it impossible for Luke to really stand up to Palpatine. But the Jedi way is not to fight using power, but to embrace others as they are. When Luke accepts his father and himself as they are, he becomes a full Jedi and his father sees what he thought was impossible: that getting angry and accessing the Dark Side is NOT a permanent pathway to doom. You can CHANGE YOUR PATH and try to atone for your sins. Being a Jedi is about the idea that NOTHING is absolute. This is why Obi-wan and Yoda fail and Luke succeeds, he is the only person to try to change and improve and not see the Dark Side as a permanent hell but something to be overcome. (This also makes the Luke we see in TLJ nearly impossible to support, he’s undone learning that cost him nearly everything to earn in such a silly way, it’s practically unbelievable.)
I would like to see a “dear leader” type of Sith someday even though it goes against that philosophy. I’m a sucker for sci-fi dystopias so I’d like to see more stories like Andor; only a step further, where it feels like most of the galaxy is in support of the Empire(or whatever faction is in power) and you have a “evil corpo” kind of Sith in control. Thrawn is probably the closest you can get but I’d like a character who can tap into the Sith/force lore as well.