I give Oda a pass for Dressrosa because it is just so clear he did not feel well. He was sick and had surgery, and they even said he should take a hiatus, but he refused. It has enough wrong with it to leave me babbling for hours, but even in artistic presentation, it just felt like the author had... changed, completely, from the one in Punk Hazard, especially by around chapter 50, where it just lost all momentum completely.
WCI has great pacing at first. And I actually appreciated the Kata fight being long, it was the way it was implemented butchered beyond recovery any tension or hype. One Piece has always given us very good reasons to have the villain and Luffy duke it out, usually with a friend's or friends lives at stake.
With Kata, it was a foolish and very stupid choice. Especially with the much greater threat (Big Mom) after his crew while he stayed and trained CoO, however amazing that ability may be. His actions were by his own admission, selfish. And in the worst possibly way. If he'd already gotten Sanji out, his friends safe, it would've been totally fine. It was a place where we could get this manly need to just confront a powerful foe and, while learning from the experience, defeat them. But nope.
This is how it should have been done, imo: Everyone actually manage to find a mirror in Whole Cake Plateau before or after the bombing, my preference being right in the middle of the collapse! Chaos!
While this chaos is going on, Katakuri calmly navigates after the Straw Hats and grabs Luffy so that he is pulled into the Mirror World as everyone escapes. Bege says this is where they part and rushes through another mirror, leaving the Straw Hats to deal with Kata alone.
Nami and Luffy both believe they can defeat Katakuri, given their victory over Cracker, if they and everyone else work together. But alas, even with Nami's rain and Jinbei's fishman karate, Kata is always one step ahead and is in danger of killing the weaker ones, namely Nami, one by one.
And then he suddenly reveals his objective was to distract them so he could free Brulee, and now everything has changed. Luffy and friends manage to get a hold of Brulee a second time, and Luffy orders them to all make for the Thousand Sunny, but is trapped by Mochi and can't go with them. He promises he will be fine. They object, but Luffy forces them all through and then shatters the mirror. He turns back to face Kata.
"You're about to say, 'I won't let you hurt my crew!', right, Strawhat?" says Kata. He twirls his trident, which flicks a little of Nami's blood, making Luffy scowl darkly. Kata's face is also shaded with rage. "Well, the same goes for me! Return Brulee, and I promise this spear won't touch them."
"I can"-
-"get that result by beating me here," Kata finishes for him. "You're about to understand just how hopeless the situation is. If you can't change that future, I am going to kill you here. And then I'll hunt down your dangerous crewmates. I won't take you lightly like your previous enemies, StrawHat Luffy! Not after you hurt my family!"
Or something along those lines. Imagine it then: his friends escape, but Big Mom has been sent directly after them with Persopero. Luffy cannot reach them and is now fighting for his life. His sacrifice has bought little real time. If he wants to do something at all, if he wants to even survive, he must survive, and win, or else Kata will eventually get to them all.
Brulee escapes and that leaves Luffy doubly trapped. Kata breaks for donuts, and the revelation of his habits leads to a similar conclusion as usual. Same general plot, but with FAR, FAR higher stakes, with a structure that makes the fight one of desperate necessity.