I think the bigger issue is how generic the isekai worlds are. The isekai genre is actually a great tool to do some great world building as you get to discover the world along with the main character. The problem is that most isekai (or even plain fantasy) worlds are identical. Here's the Adventurer's Guild, here's the elves, here's the kingdom (who happens to have a princess that the main character can conveniently rescue). There's not a lot of world building going on when every world is the same.

The Wheel of Time actually has some of the isekai elements (it is still a regular fantasy however). The main character comes from an incredibly isolated part of the world and is thrown into the rest of the world where everything is foreign and strange and that lets us see the world being built by the author around us despite the situation being basically the same as in an isekai.

As for character motivation, I don't think that is inherent to the isekai genre either. Excepting stories like Overlord where the main character is actually just clinically insane, most authors don't properly reflect on how it would affect a character to be thrown into a foreign world. "I'm a go register as an adventurer!" is not a realistic first reaction to being isekai'ed.

which is not the case for a japanese team that spend his life playing Kancolle giving advice on what people oppressed by war should do.

I actually think this could be an interesting element to explore in an isekai. A person coming from the modern world into a medieval one is gonna have conflicting morals with the locals. Seeing how the main character has to come to terms with this could be fascinating.

I might step on a few toes here, but in the end isekai is a from of escapism. That is why stories like Arifureta are popular. The main character is a social outcast and the story is about the sudden reversal of that situation. There is probably more than a few readers who can relate to that and like dreaming of that same thing happening to them.

Isekai is not a bad genre in itself, but there is too much lazy writing and catering to the audience for it to have produced any masterpieces in my opinion.