OMG THANK YOU. I thought I was the only one who felt that way. I've read probably more than 10 isekai Mangas and give up on a lot more than that. They always just annoy me because 99% of the time they add nothing to the plot other than as a lazy excuse as to why the lead has "unknown knowledge" or is intelligent. It just feels like really lazy writing to me. Especially seeing as apart from the first chapter (sometimes only the first few pages) you never see their original world or body again. It's just some dumb and pointless and adds nothing to the story other than to explain why the lead knows a bunch of stuff whether that be about the future or about ideas to improve the world. I don't understand the point. What makes it worse is that the majority of the time the actual story has a good plot. The actual plot of the story is interesting and really good so I don't understand why it needs to be "ruined" by the random plot point that barely goes past the first chapter and is essentially a cheat. So far I've only read maybe 2 or so Mangas where the isekai part plays a key part of the main story. It just annoys me.
Like, I’ve read good isekai where I see why the isekai element is necessary, either completely or somewhat, but then there’s some that are just like.... you know, there are pretty easy explanations you could use for this instead of “isekai”.
Is this another "isekai for the sake of isekai"? Her sister has a boyfriend of the lower class. She doesn't want to go help his highness. This has been established. She even understood why her sister went instead. So why is the isekai element necessary?