My problem with JJK

While overall JJK is definitely a decent series (and one of my personal fav), I still have problems with it. Here's the list:

1. Nobara's status. It was left unknown for more than half of the series, and Gege only revealed it the last 5 chapters, which sucks cause there's definitely more to her character that Gege can use rather than throwing her whole character away for the most part of the story. Maybe Gege wanted to throw away the "trio shonen cast + teacher/master" trope, but how its done was disappointing.
2. Merger. For one, I don't think the Merger should happen at all considering the requirements of it happening is the death of all players (which would include most of the main cast excluding Gojo, Choso, and probably the teachers as well as Maki). However, I feel like Gege "hyped" the Merger way too much (by making the readers way too curious about it), people start believing it WILL DEFINITELY happen.
3. Yuki. I don't really need to explain why, she got every single potential to be more than just one-off character. (I still loved her character til the end though, I just feel she's very wasted)
4. Heian era arc. A lot of people wanted this arc so we can explore more about Sukuna's character, but I think this would be the perfect arc to show more about Kenjaku and Tengen instead. I don't need Sukuna's flashback, as most of his history and his point of view are explored heavily throughout the series, but we barely know about Kenjaku and Tengen.
5. The performance of some characters in Shinjuku Showdown.
   1. Maki. She got so much hype, starting from stabbing Sukuna, capable of going toe-to-toe in a physical fight with Sukuna, and eventually getting praised by him, for all of it to amount into nothing. She did no long lasting damage, and what started out as somewhat an even fight with a very weakened Sukuna turns out to be nothing as Sukuna would eventually overpower her without even using his CTs. She would eventually need help from Miwa to counter Sukuna's domain. Yes, that useless Miwa. Imagine being regarded as a "Monster" and needing help from arguably the most useless character in the whole series.
   2. Miguel and Larue. I don't see any reason why they should join the fight. Not long after they join, the rest of the fighters join the fight again, and they (like Maki) did no long lasting damage. Even worse, they left the fight just after 1 chapter. It kinda feels Gege just looking for more characters to add for no reason, considering he would eventually add Todo and Nobara later on, which did much more.
   3. Yuta in Gojo's body. Other than to improve Yuta's character (which has been explored well enough, considering he has his own story and being one of the master planner behind this fight), there's literally 0 reason for him to come back other than the fact Gege is trying to prolong the fight that sometimes feel a bit longer than it should be.
6. Kenjaku and Yuji interaction. The only time we have them interacting is during the end of Shibuya, and that's it. Considering Yuji is his creation (and possibly his best creation), it's crazy that they have no other interactions ever again, unless something is revealed in the last 3 chapters.
7. Lastly, Hakari v Uraume. Look, it doesn't really bother me how their whole fight is just a bunch of nothing, and I truly understand why Gege sidelined this fight for the main event and Kenjaku's fight. However, it does feel a bit sad that one of the expected heavy hitters from the good guys and Sukuna's number one dickrider had an overall offscreen fight. No technique reveals, not much character story progression between the two, and a bunch of yapping.

One thing I don't hate, however, is Kenjaku. Yes, there's really nothing much we know about this guy, there's no clear explanation of his relationship with Tengen or even Sukuna. All we know is he did everything for fun, and thats it. The making of death paintings, giving birth to Yuji, and The Merger was simply to... have fun. I get why people are disappointed in him, as he died like a clown, but the whole idea of his character is to (again) have fun. Everything he did, all of it, literally means nothing, as he's just curious and wants to find out the possibilities. This is just my interpretation, but looking back at the end of Shibuya, it seems like he said the world needs to rely on cursed energy simply because he was curious, not because he has a grand plan of being a higher being or anything. He eventually meets his end by having fun, by "playing" a lot with his weird opponent, Takaba. He even learned much from his Takaba, considering Takaba's cursed technique is quite unexplainable. With that, I find that his whole character comes to a full circle, the guy who does everything for fun, without regards of how others perceive it, eventually dies by having fun.

Well that's it for my whole yap session. What about you guys? What do you think is the weakest aspect of JJK?