I'm not a huge fan of the isekai genre, but that doesn't mean I hate it either; its ubiquity is what makes me wonder why people don't just make straight up fantasy anime.
Frieren for example would be terrible if Frieren was actually some random person from earth who got sent into her setting (or, as Frieren's whole thing is outliving her comrades, her purple haired protege was the isekai'd protagonist); I understand how the isekai nature of an anime can also affect the anime, for example a character who has modern world knowledge he applies in the setting, or modern world tech, but if he just becomes a part of it, and NOTHING from his real life has any impact on the setting....then what's the point?
Overlord for example (which I didn't enjoy to be honest; I googled if he ever faces a challenge and nope, entire series and he has zero things that can challenge him) would not have been affected if he was just some lich who woke up a thousand/hundred years later.
Konosuba benefits from the isekai genre in that the isekai elements keep being relevant throughout (Spoilers:
spoiler
for example that guy who chose to reincarnate into the world with a powerful sword that Kazuma stole, or Kazuma dying and Aqua's replacement reviving him repeatedly, or that the demon lords at some point realized all their most annoying hero enemies keep starting in this one town and so decide to attack it, or that ancient scientist who turns out to be have been an isekai'd hero who creates stuff inspired by stuff he was a fan of
Most isekai animes today just seem to be wish fulfillment harem animes, which are a problem on their own as well, but they're paired with being isekais too (if you're wondering why I didn't make a thread on wish fulfillment harem animes, it's cause by and large I avoid them like the plague).
There are some interesting POST isekai stories that I found fascinating, stories where the characters came back from the isekai world and had their powers with them; in one case some of the heroes become devastatingly powerful villains who destroy entire cities, in another case it's a comedy about some guy who comes back and....could have been funnier without the ecchi/SA nonsense happening throughout.
Animes like SAO (which I didn't find interesting beyond the first story) make the other world an entirely false world and never let you forget the characters are real people who can actually die in the real world (sort of an anti-isekai genre).
In general, if they're not going to benefit from being isekai....then just make them normal fantasy. So many good fantasy animes out there that would have been hurt by making the protagonist just an isekai'd character.
The Korean comics I like that're also isekai raised the bar so high for me that it's been impossible for me to go back to reading any Japanese comics. Like most of it goes back to Korean comics being not (as) freaking pedophilic or sexual to the point of competing with the storyline, but I find that Korean isekai style stories tend to be more varied and vibrant with their hooks and story plots in how they integrate the whole "normie in another world" bit.
Like I'll hoot about my fav again, 'The Greatest Estate Developer' an isekai about some Korean dude that's near the bottom rung of society and likely to work himself into an early grave get plopped in another world that's exactly like his favorite fantasy webnovel into the body of the son of some countryside noble. But instead of being some lustrous aristocratic blue-blooded elite that's waited on hand-and-foot or some sort of ubermensch power trip of a character, the body the Korean dude took over is a normal fucking aristocrat, as in a shitty person that terrorizes the people while constantly engaging in excessive hedonism. His powers? A sort of gaming UI system screen pop up that shit talks him and the body he's inhabiting. What does he do with the fact he's isekaid and he's a fuckin normie? Nope, no slave buying, no fancy fucking wowie wowza chemistry to make guns, nah dude gets a fucking shovel and makes an ondol (house with heated floor) for the innkeeper whos inn his body's previous owner trashed before he isekaid there.
His entire story is about him busting his ass to improve the material lives of the people regardless of where they're from or what they are. It's just a good story.
Hell even the more cheesy basic-ass isekai slop stories like the comics "I Shall Live As a Prince" or "The Novel’s Extra" are refreshing in comparison to the many of the isekais that're considered top quality on the Japanese side.
The comic did a lot of elevating for The Greatest Estate Developer, iirc his personality is pretty different and more bogstandard isekai chump in the novel, but still within the Korean versions standard.
That's the wonderful part of the Korean side of webcomic making is how they let the team they're outrageously exploiting at absolutely wild breakneck production speeds the ability to alter their product to their tastes