People really didn't like the lightsaber fights in the prequels? If anything I'd say they are one the things better in the prequels. While there's certainly an emotional, nostalgic response to be had to the duels of the originals, they are slow and clunky. Ep IV's Kenobi vs Vader was very unimpressive, specifically. I have the image of Kenobi's old man spin move burned into my brain.
The prequels, on the other hand, were very well choreographed with each Jedi/Sith having their own unique style. And emotion, in many cases. Anakin vs Kenobi (ep III) is, IMO, the best duel in the series. The greatest Sith warrior vs a Jedi Master. The end-all battle that the whole series led up to. Emotional and stylistic.
Were there unnecessary, gimmicky fights? Yes. But the best of the prequels trumps the best of the sequels.
I just watched both the final duels of both trilogies. Here are some thoughts:
Episode VI's duel is all about Luke facing the temptation of the Dark Side. Episode III is all Kenobi acknowledging it's time to put Anakin down, and having those two go all-out against each other while showing off new technology.
There's a genuine build-up going on in VI. At first, Luke refuses to fight. He doesn't want to be tempted by the Dark Side at all. Vader takes swings at him, but all Luke does is parry, and run. You can tell that he wants to bring Vader back, and that he still has hope. Only after a long period of baiting does Vader finally draw Luke's dark side out. Then, there's all sorts of cleaving and swinging going on from both participants. But, there's an art to the scene. It takes awhile before Vader draws Luke into fighting to kill, which emphasizes the difference between the light and dark sides of the force. The same emphasis, by that way, that's placed when Kenobi completely yields to Vader in Episode IV.
Not so with Episode III. In III, you have Kenobi and Anakin going for the jugular right away. As soon as their lightsabers are drawn, it's understood the fight will be duel to the death. And, why not? In previous episodes, light side Jedi have ended duels by hacking off the limbs and heads of their dark side opponents. So who cares?
Episode III's final duel is like a big fireworks display. It's awesome, but it doesn't mean anything. There's tons of pyrotechnics and explosions going on to supplement the action, but there is nowhere near the emotional and psychological pull of Episode VI's duel.
Now, why I think Episode I's duel works, while Episode III's doesn't: first off, length. III hits its climactic height early, and stays in the same place for a loooong time. Not so with I. Episode I's duel is just about the right length, and the choreography and music are extremely well done. Kenobi fights as you'd expect Kenobi to fight, with the intention of putting Maul down only when it's abundantly clear that there is no other way. And, Maul is practically subhuman. He's red and black, with thorns growing out of his head. He's like an evil demon, or something. It makes sense that Jin and Kenobi would want to take him down immediately. The fight doesn't need the same emotional build-up Jedi-artistry that Skywaker/Vader had in Episode VI, or Skywalker/Kenobi sorely needed in Episode III. It's just two Jedi putting down what is practically an out-of-control animal. It's just a good fight. It's not really a duel, but an arena fight.
The original trilogy has duels. All of the Jedi fights in the prequels are arena fights.