^Agreed. When I first saw Greedo shooting first, I really couldn't figure out what was happening. The 2004 special edition improved on the 1997 special edition by making it more of a quickdraw situation but it was still unnecessary.
And I'm another fan who is sick of everyone else badmouthing the prequels! (A pastime that has become even more popular since
Episode VII was announced.

) While the dialogue is frequently weak and
The Phantom Menace is mostly irrelevant, the films are frequently bursting with visual inventiveness. When I rank the films,
Revenge of the Sith &
Attack of the Clones are #1 & #2, respectively.
The follow-ups were a mixed bag. The sequel movies were pretty bad, but the spin-off TV series actually did a pretty good job of making the basic immortals concept pretty consistent and even added some good, interesting pieces to the mythos (the Watchers, Methos). Then came the final straight-to-video movie that dumped it all into the trash again...
I was never really able to get into the TV series but I loved
Highlander: Endgame. Highlander II has a lot of backstory that totally doesn't match with the first movie but has some brilliant set pieces. It's ingeniously insane!
Highlander: The Final Dimension is a depressing rehash of the first movie.
Highlander: The Source is worse than you could possibly imagine. It's so forgettable that it ends with a flashback recapping the movie that you just watched. (Thankfully,
Highlander: The Source doesn't count because it went straight to video and because it's villain doesn't have a "K" name.

)
I can think of something kind of like that. I went and saw 'Love Never Dies' with my mother when it was in Sydney, and she had never seen or read any incarnation of the Phantom of the Opera. A while later, I watched a recording of the musical POTO with her, and during the finale (where the Phantom is trying to lynch his romantic rival whilst the heroine bawls) I started going 'Look mum, he's her true love!' whilst she sat there looking shocked.
Though I wouldn't say that 'ruined' POTO for me.
I'd seen
Phantom of the Opera a couple times but I'd never heard about what happened to
Love Never Dies after they first announced it. I just read the synopsis on Wikipedia and GOOD LORD, WHAT WERE THEY THINKING?!?!
A sequel being bad doesn't ruin the original, but a sequel can undo the ending of the original or change the fate of the characters and that can ruin the original.
Like, Terminator 3 reverses the ending of 2 to justify itself.
Of course,
Terminator 2 already reversed the perfect predestination paradox that was
The Terminator. Or at least it tried to. In my head-canon, the 1st 4 films are all part of a single closed loop. I just ignore the details that don't fit, like different dates for Judgment Day or the T-X successfully killing some of John Connor's lieutenants. (Since they all seemed to live in metro L.A. at the time, how did they survive Judgment Day in the original timeline?)
But just imagine how the fandom would have exploded had they gone with one of the earlier endings for
Terminator Salvation. (John Connor dies and Marcus Wright takes his identity as leader of the resistance.)
An even better example: Does anyone really think that the original JAWS was "ruined" by JAWS: THE REVENGE?
No, but
Jaws 19 did! What a piece of shit! The shark still looks fake.
The opposite happens more frequently for me. Despite it being his most popular work, Gremlins is not my favorite Joe Dante movie, but the sequel being such inspired lunacy that does riff on the original quite a bit makes me like it more than I probably otherwise would.
Similarly, the live action Addams Family movie has a great cast but a so-so script. Addams Family Values on the other hand is one of my favorite comedies of its era, and enhances my view of the original by its connection to it.
Agreed. On the list of sequels that vastly improve upon the originals,
Addams Family Values &
Gremlins 2 are at the top of the list.
I can't really recall sequels that "ruined" the originals for me. The one that came closest was
Pirates of the Caribbean: At World's End. The way it left things with the Will/Elizabeth romance was a major bummer and Jack losing the Black Pearl again was a disappointment. Add in the unnecessary deaths of Governor Swan & Admiral Norrington and it seemed like just about everyone other than Barbosa ended up in a worse place at the end of
At World's End than they were at the end of
The Curse of the Black Pearl.
It was kind of a bummer that they kept killing off beloved characters in the
Rocky sequels-- first Mickey in
Rocky III, then Apollo Creed in
Rocky IV, then Adrian during the gap between
Rocky V &
Rocky Balboa.
I can recall some lackluster sequels that severely dampened my enthusiasm for the franchises. I haven't been nearly as interested in
Star Trek ever since J.J. Abrams' time travel reboots. Robert Downey Jr.'s
Sherlock Holmes movies made a fatal mistake when they killed off Irene Adler at the beginning of the 2nd film. (If they make another one, I keep hoping it's either a prequel or that they reveal that Col. Moran helped Irene fake her death.)