But Vader was just as beloved (albeit in a totally different way). For some of us, what the PT did to Vader is worse than what TLJ did to Luke. You can disagree, and I'm sure you do, but it's never going to evolve into an objectively provable issue.
Reducing Vader (in my opinion) to a whiny, love-lost, and easily-manipulated figure was compounded by making his necessary turn against the ones he cared about most seem like it all happened for horribly-established and nonsensical reasons. That was unforgivable; it was too important of a story point. The rationale, as shown/presented in the PT, was insultingly flawed on intellectual and cinematic levels (again, only my opinion). A worthy story-telling justification is what a lot of us wanted/expected for the long-anticipated on-screen fall of Anakin Skywalker. We didn't get one; we got the opposite. As others have said, it was even laughable. Not just the dialogue, acting, and visuals of the PT; the story too. Therefore, that's why I could just as easily argue that the PT took "a steaming dump" on the OT's beloved/respected villain.
I'll spare you all of the justifications I've used before for Luke's shift in the story, but they're no less valid than the contrary objections. Some here have offered justifications for the Vader turn in the PT. They don't work for me, and I don't think the TLJ Luke justifications will ever work for you either, but TLJ wasn't the first (or worst, IMO) SW film to need justification for poorly-received story elements.
You're a great fan of Star Wars, TaliBane, and I admire that a lot. You want to preserve everything about it that made you a fan. TLJ betrayed you on those levels, so you resent it more than you do the PT. Some people (myself included) feel the reverse: the PT did more harm. Star Wars diluting Vader (heavily), and the saga becoming a point-and-laugh-at-it joke, was worse to me than what TLJ did.
Sometimes it can seem that anti-TLJ comments lose sight of the fact that fans found more egregious harm done to SW several years ago than anything Rian Johnson (and others) did to SW last year. For many of us, the PT was a low point that needed to be followed by something - anything! - less hokey, embarrassing, and poorly presented. That can lead people like me to blasting the PT all over again in order to provide perspective and context amidst the "TLJ destroyed Star Wars" comments. Mistakes have been made in the ST to be sure (some of them big ones), but I don't think any of the on-screen ones rise to unprecedented levels in the SW franchise.
