One of my big problems with the Harry Potter series is how Rowling clearly just threw in things that she thought were cute or clever, without bothering to think about how they would actually all work together.
I've already made it clear that these Doraemon books are not for me, because I can't get past how it's an amoral nightmare full of terrible people who seem to spend most of their time being awful to each other for no reason.
But having read two volumes in the series now, I'm increasingly bothered by how Rowlingesque things are. Naturally, you can't ask a random serialized manga for small children to have a Tolkienian foundation of worldbuilding under it. But it doesn't really seem like the author knows or cares much about their own work, here. Many issue-of-the-day chapters center around a pointlessly specific device whose function is entirely subsumed in other, more powerful devices that other chapters had already introduced. Meanwhile, other devices (like the take-copter) make random appearances at some times for convenience's sake but remain weirdly absent at others.
Fujiko-sensei is clearly a deep wellspring of creativity. But having seen so many manga and anime where the entire shtick is "let's explore every possible use and implication of this one thing," I find myself with limited patience for a world that says "sure, time travel and doors-to-anywhere and cameras that reveal the past exist, but let's help Nobita go shopping and watch TV at the same time by cutting him in half and giving his legs their own separate sentience!"