Isekais are popular the same reason junk food is. They're both easy to digest and taste pretty decent, but at the same time most of them are trash. Unimaginative settings, crappy characters, crappy plot, etc.
Honestly I don't know why I expect something more when I'm trying to read an isekai. Most of the time there isn't that much conflict. Its just the MC gaining more and more power cause he's the MC. The love interests aren't that interesting too; most of the time they're just otaku fantasies, and others who have potential become people who can't seem to function without the main character, and if that isn't the case, they get overshadowed by the MC's bullshit instead. Where's the love interest's agency? Why are they only defined by how they wanna get into the MC's pants?
And the most important question, why the fuck do I bother reading this shit? Fuck this genre's target demographic honestly. And fuck me for being trash enough to tolerate this crap in the first place.
TL;DR - I hate isekai, but I'm just as trash.
Honestly, the only "advice" I can say is, try other genres... the fluffy romance genre's pretty loaded considering its popularity nowadays. Fluff is pretty inoffensive, but I can definitely say its miles better than your average run of the mill isekai. Also, sports and shounen manga are pretty samey, but at least they preach the values of hard work and determination. Hell, i contradict myself that the villainess genre are better, but that's just like saying fried chicken's more nutritious than potato crisps.
Typing this out made me realize something too... most manga are mediocre as hell. Not just manga too, this includes anime, live action movies series, etc.
So don't be afraid to drop series you don't like, and don't be pressured by the community to like something that's not to your taste. And don't expect for a genre to be better in time when its history states otherwise. Just like toxic relationships, cut that fucking shit off. Life's too short for BS, and isekai is grade A Bullshit.
Edit: that was a bit more emotional than I wanted. damn haha