A lot of the time, the stories of the Star Wars franchise can usually get boiled down to a simple battle between good and evil, with phenomenal and complex characters, electric dynamics, and a plethora of brilliant themes like family, friendship, hope and others threw in. All this helping create the brilliance that is Star Wars.
Therefore, the villains of the story are of equal importance to the heroes who have become so beloved and iconic. Throughout the franchise, the heroes come out on top, with villains usually getting what they deserve; some did get off easier than others, though.
Watto
In terms of this list, Watto is representative of all of the low life scum and villainy in the Galaxy who do not have much real power but are still total scumbags.
We do not yet know what happens to Watto in canon, but he is alive at the rise of the Empire. He was a human trafficker, caught up in gambling with the Hutts, as well as a slimeball, and a generally bad person.
Captain Phasma
Captain Phasma is another awful person. She did meet her end on the Supremacy, but other than getting forced to help blow up Starkiller Base and put in a trash compactor, she did not get much comeuppance.
Phasma was an important member of the First Order in charge of training stormtroopers - deplorable in itself. However, she was not even loyal to the First Order; she assassinated Brendol Hux, the man who brought her into the First Order, she was selfish evil at its finest.
Maul
Maul is a pretty tragic character making it hard to put him her. Ripped from childhood and thrown into the Dark Side, and surviving through singular hatred and anger, constantly getting taken down a peg, somehow, no matter how far ahead he managed to get.
Nevertheless, Maul came back, again and again, performing heinous acts and unleashing chaos and evil on the Galaxy. Whether it be by ruling Mandalore, killing Duchesses and Jedi, ruling the criminal underworld, Maul was evil, and even though Obi-Wan had the arguable right to make him suffer, he gave Maul a respectful end.
Kylo Ren
Darth Vader is not on this list, even though he did worse things than most people on this list he had such a tragic story, and suffered so much every day, haunted by the thought of Padmé, by his master, and from sheer physical pain, his life got seduced out of his hands.
Kylo Ren, while redeemed, was seduced to the Dark Side, did not have as tragic a story as Vader, nor did he suffer as much, and his motivations were not as clear cut, layered, or relatable. Kylo had moments of clear vision, usually brought on by Rey, and never sided with them, always wanting to go back to the darkness, he destroyed planets, slaughtered villages, murdered his father, and probably deserved a bit more punishment. Still, his similarities to Vader and his redemption can be argued otherwise.
Grand Moff Wilhuff Tarkin
The secondary villain of A New Hope, Grand Moff Tarkin, died on the Death Star, but such a quick defeat, which he never even noticed, was not the type of consequence he deserved.
Through the Tarkin book, Rogue One, and The Clone Wars, we know Tarkin is pretty much a Nazi and an utterly abhorrent man, who caused immense death and suffering.
General Armitage Hux
General Hux got shot for being a spy for the Resistance. However, he was not even a good guy spy; he was spiteful and wanted Kylo Ren to lose.
That sums up Hux, a man so single-minded and deplorable, who conspired with Phasma to kill his own father, who was key in destroying an entire system, who deserved a bit more consequence than just getting shot.
Count Dooku
Count Dooku was not only a fallen Jedi and Sith Lord, but he was the leader of the Separatist Congress and the apparent leader of the droid army.
Even without the evil nature of the Sith, which is obvious, Dooku deceives droves of good people who are Separatists. He is a pawn in Palpatine's scheme, a scheme which Dooku believes he knows and has a place in, but even despite this betrayal and subsequent death, Dooku earned more of a punishment.
The Grand Inquisitor
The Grand Inquisitor was the head of the Inquisitors, trained by Darth Vader to hunt the surviving Jedi and kill them. He met his end in the season one finale of Rebels, but in a twist, he welcomed death, he, in fact, was the one to die willingly, Kanan did not kill him.
"There are some things far more frightening than death." The Grand Inquisitor's last words show the audience that he deserved harsher consequences. He was not scared of death right there; he was scared of the alternatives, alternatives that he deserved to face.
Jabba Desilijic Tiure
Jabba the Hutt was choked to death, and after said death, his barge and compatriots were killed. However, for someone as hideously loathsome as Jabba, he got off lightly.
Jabba ruled upon a crime empire, which included drugs, piracy, and trafficking. Everything about him is execrable, and Leia gave him an easy death, no matter how iconic it was.
Sheev Palpatine
Emperor Palpatine's two deaths do not do justice for the unbelievable evil that exudes from every inch of him, and every one of his actions.
Anything that involved Palpatine's plans getting thwarted by way of him suffering, or having something taken away would be a bit better in terms of getting the consequences he deserved. Ultimately, Star Wars does not promote war, suffering, pain, or revenge. These individuals have done some evil things and deserved comeuppance, but as long as the consequences they did get brought peace, prosperity, and justice, that may well be enough.