Get personal, I'm not sensitive.
It wouldn't be new for creative or interesting for Luffy to lose to an opponent though, which you seem to want, eh? We've seen that with Crocodile, Lucci, Ceasar, Magellan, the entirety of Marineford. It's not new, but I don't think it happening the way you seem to intend and right now would bode well at all for a fight with Kaido. If Luffy is to power up and be forced to get stronger, it should be for a Yonkou, not a lieutenant. If he doesn't have a way to get around a guy on Katakuri's level, the timeskip was a waste.
Plus, we're at the right place with this. Luffy knows his weakness; actually vulnerability is a better term. That he needs extreme amounts of composure to use his color of observation the way he needs to. And it's not as if we all haven't been wondering what's made Katakuri so special, or how he seems to appear like a Logia. We were given an answer to that question and understand that his main strength is also one of his biggest vulnerabilities. Would you rather Luffy just come back, stronger, awoken, and better with Haki? I suppose that's an answer, but to me it's not the right one.
Creativity here isn't in the fact but in how it's presented, i wouldn't have minded him winning if it involved something other than exploiting a vulnerability tailored to fit, sure it's amusing, we all laughed at seeing Katakuri's true self, but i don't want Luffy's first solo victory against a top tier fighter to be because of a gag. As you said i'm not nearly as creative as Oda, so i couldn't offer you an alternative in this situation, but then again, he's the one who put himself there, so i'd expect him to solve the matter in a satisfactory manner.
There was no mention of "extreme amounts" of composure, you need to be calm to use CoO that's all, it's nothing exclusive to Katakuri. As for his power i think it was made public a while ago that it was only changed from Logia because he isn't made of a natural element, so we didn't really learn much, we saw him move like a logia, create and shape matter like a logia, and go beyond that to control it at will. If anything his power is more OP than a logia.
The thing is, Oda seems to want us to believe that Katakuri's only been doing so well thanks to his CoO when he's previously spent chapters showing us that he in fact outclasses Luffy in speed, power and technique. Now most people seem to think gear 4th makes Luffy a God (he clearly seems to think it himself), and that i don't buy, not after the struggle against Doflamingo or the lackluster performance against Cracker. Luffy shouldn't be able to win, and if the best Oda can think of is this, well I'll have to accept it and move on, but don't tell me it's creative or an interesting turn of events.