It’s not a matter of it being “hard to believe”. I don’t like it. You can’t take a character ppl love, take away from some of what they loved about him and expect ppl to be cool with it.
I completely understand where you are coming from, and I respect your love for the way Darth Vader is portrayed in the Original Trilogy. However, I think it is unrealistic to expect him to be as agile as he was before he got the suit, especially after everything that happened to him in Revenge of the Sith. As I have already said, the guy had both of his legs and one of his arms cut off, and then he was left to burn alive for hours before Palpatine arrived on Mustafar to save what little was left of him. After going through all that, it wouldn’t make sense for him to move with the same speed or agility. However, his physical limitations are part of what makes him so intimidating, at least in my opinion. The fact that he can still fight with such ferocity despite those injuries shows how powerful he really is. Even though his mobility has been reduced compared to his younger self, he has learned to adapt. He is no longer the fast, acrobatic duelist he was as Anakin, but now he is this unstoppable force who fights with pure power and precision. His strikes are heavy and deliberate, and that makes him terrifying in a different way. So, I think that his reduced mobility actually makes him even more intimidating. And let’s be honest, just looking at the suit, it is clear that it is heavy and uncomfortable. It is not the kind of thing anyone would want to live inside, much less fight in. You can tell right away that it would restrict his movements. But that only adds to the character in my opinion, because despite the fact that the suit looks cumbersome, Vader still manages to dominate his enemies. It is part of what makes him so menacing — he is pushing through immense physical pain and limitations, yet he is still one of the most dangerous beings in the galaxy. That’s what makes him powerful, even if he is not as agile as he once was.
Making the Jedi corrupt means there’s no good role model. That’s the role Obi-Wan and Yoda have in the OT; they’re the good mentors leading Luke to the enlightened path. You need that in a story that, while for everyone, children should be able to follow, unlike The Godfather, clearly for adults.
I understand your perspective, but I don’t think the Jedi need to be perfect to be role models. In fact, showing their flaws makes the story more relatable. The idea that “everything was perfect until Anakin and Palpatine destroyed it all” is way too simplistic, because life is not that black and white. People and institutions, even well-meaning ones like the Jedi, can make mistakes, and those mistakes can have serious consequences. A Republic that has lasted for thousands of years does not collapse simply because a guy with a bad childhood and an evil sorcerer decide to team up. Things are not that simple, and it is wrong to portray them so simplistically. There is a reason why people these days don’t appreciate simple fairy tales as much as they used to, and that’s because real life doesn’t work like fairy tales, and people don’t like simplistic stories anymore. There is a difference between trying to be positive and spread a good message and writing unrealistic stories where the good guys are perfect and the bad guys are basically demons with no soul. Furthermore, what makes Obi-Wan and Yoda compelling mentors is not that they are flawless, but that they learn from their failures. They are still guiding Luke toward a better path despite the mistakes the Jedi Order made in the past.