Two main reasons: It kept Vader strong with the Dark Side. The constant pain meant that Vader had to continuously draw on the Dark to keep the everlasting agony at bay. It kept Vader a slave to Palpatine.
However, the transfer into the suit would have been agonizingly painful. To Vader, there would be little point in doing so, especially considering there remained the possibility he'd not survive the procedure. On top of that, Palpatine designed the suit to be painful to Vader.
Darth Vader's Suit Embeds Needles In His Skin
Unfortunately, these needles, which transmit neurological data throughout his body and allow him to control his limbs, also cause him constant pain. Between the never-ending itchiness and walking around with needles in his skin, it's no wonder he is so angry.
So Palpatine may have been trying to accelerate Vader's dark side training by giving him more pain to fuel his power. And if it also prevented his apprentice from challenging him, all the better.
Before canon it was stated in "Legends". That he was in constant pain, the suit was uncomfortable and purposefully so, since Palpatine never wanted Vader to reach his full potential.
He can only breathe without the need for his mask when he is in one of his meditation chambers seen in The Empire Strikes Back.
Darth Vader's armor, also known as Darth Vader's suit, was a suit of armor worn by the cyborg Sith Lord Darth Vader. Designed with life support technology, the armor ensured Vader's survival following the lightsaber and burn injuries that he sustained in a duel with Jedi Master Obi-Wan Kenobi on Mustafar.
Despite his somewhat pure origins as a Jedi, Darth Vader definitely has plenty of moments where he genuinely enjoys what he does on the dark side.
And while the suit did keep him alive, it also hindered Vader's abilities and potential as a Force-user. But unknown to Palpatine, this decision would result in his demise. Darth Vader was still undoubtedly powerful, and the suit made him more intimidating than Anakin could ever be. But the suit also limited his power.
Anakin would have likely been killed by the clone troopers, along with the other Jedi. However, perhaps he would have escaped. He would have taken the pregnant Padme with him. He would have needed to get as far away from the eventual Empire as possible, so perhaps they would have gone with Yoda to Dagobah?
Purpose. Darth Vader's meditation chamber was a life support pod that allowed the Sith Lord to survive for extended periods without the helmet and mask of his suit. The injuries Vader sustained during his duel against Obi-Wan Kenobi on Mustafar normally made this impossible.
The short answer is yes, without a doubt, Vader regretted becoming a cybernetic monstrosity.
However, when he found out that Luke was his son, that was when he started to regret his decisions. Vader became conflicted about the fact that he had a son. This was the first time he regretted his decision to turn to the dark side in many years.
In Star Wars Legends and Canon, Galen Marek (Starkiller) is the only Jedi (other than Obi-Wan Kenobi) to put a beat down on Darth Vader/Anakin Skywalker.
Anakin's tragic flaw was his fear. This was the reason the Jedi council restrained him from being a leader for the simple fact that he feared his wife Padme's death, the safety of his mentor, Obi Wan Kenobi, and he feared the safety of all the clone troopers placed under his command.
Qui-Gon Jinn is seen by many as the best of the Star Wars prequel era's Jedi, and there is evidence that he could have even stopped Anakin Skywalker from falling to the dark side of the Force.
The added risk Darth Vader takes in allowing children to live in a situation where he could have killed them proves that he regrets killing Younglings and will avoid harming any more children for the rest of his days, though intense intimidation is a dark strategy to avoid repeating his Youngling massacre.
Even after his brutal scorching in the fires of Mustafar, sand remained the only natural phenomenon that Vader feared. To him, sand was a reminder that he'd failed to save his mother or Padme from death.
During the Imperial Era, a human female nurse served the Galactic Empire on board the Death Star under the supervision of a doctor. They both served the Sith Lord Darth Vader as his personal medical caretakers. The nurse became obsessed and psychotically in love with the Dark Lord of the Sith.
15 He Can't Sleep
Truth is, he was constantly uncomfortable whenever he was in his suit, to the point that it made him sometimes incredibly insane. Vader needed to take breaks, dipping himself in a liquid chamber where he allowed himself to meditate as we saw in a deleted scene of Rogue One.
Palpatine specifically designed the suit to both make Vader feel pain, so he could channel the darkside, but also to limit his power.
Apparently, George Lucas made the lightsaber green because it looked better against the blue-sky background. But it was more than just another lightsaber. Constructing it represented Luke's status as a Jedi, and even Darth Vader recognized the accomplishment.