Isekai (another world) genre is often thought of as a trashy genre, where few shows are ever written well. And perhaps that opinion has some merit. I can't argue that it is not full of trashy tropes and Mary Sue protagonists. All that in mind I still think that people are wrong to judge those shows harshly on those qualities and here is why.
To look into the matter we don't have to look for a show far. This seasons "In Another World With My Smartphone" is a perfect example of a typical isekai anime and it's tropes. It does not play any tricks on the audience, there is no deconstruction of the genre or anything like that. It is a pure "play all the tropes straight" show. So you would obviously have a reason to ask, why I do not denounce it as an abomination to God.
To answer that question lets first look at some of the plot points in the show. There is nothing that important to spoil, but you should be warned I will talk about the plot details.
So first thing in the show is the protagonist dies and what do you think, it is totally Gods fault. Oops my bad, don't worry though he will resurrect the poor bloke, problem being that he is definitely dead in his old world, can't exactly raise the dead there, better respawn him in the fantasy world. As a boon the protagonist gets to choose one thing to bring. He chooses as you probably surmised from the title - a smartphone. A bit of an odd choice, but I guess Japanese are really into their phones. Just as an afterthought, God improves his body too (just so that he doesn't die there too quickly).
So once in the new world as he is wondering what he will do about money, some fashionista sees him and his SCHOOL UNIFORM, and what do you know it is totally novel and cool clothing design, would you sell it to me. Suddenly he has money.
Next it is about time to find a harem. Better save some twins, because every harem needs twins. What do you say? Two is not a harem? Better find a samurai girl from Totally Not Japan.
In the meantime how about we test you for magic. Oh you can use ALL MAGIC like no one ever could. Amazing.
Well a harem, erm I meant party is complete and he can fight too, lets do some quests. Lets go deliver a letter, on the road though he happens upon and saves a daughter of a duke, as the duke is thanking them a talk stumbles upon a reason for her being on the road. Apparently she was looking for someone who could heal her blind mother. What a coincidence - you can use all magic. So now you saved a daughter and a mother. You are now fabulously rich and you've got another member of your harem.
So there are more events that happen in his favor. But you probably get the gist. The protagonist is super powerful in a fight, he has a harem and he is super rich too.
Which brings us to a question. Isn't fiction supposed to be all about struggle and conflict and you would be correct for most western media. But for Japanese media it is less so. If you ever watched a slice of life show you know what I mean. Japanese care more about characters and the world and just the regular interactions. Conflict is playing third fiddle. It is not true for all anime, but a lot of them are like that. Furthermore there is one medium which both in the west and the east, share the same qualities - it's fanfiction. When creating a fanfiction you fist think of the character interactions, instead of conflict, unless you are writing a more niche fanfic. And it's not like they are small and insignificant there are millions of separate fanfics on the internet, so the demand must be there.
That's why if you are going into this anime with expectations for a serious show, you will be disappointed. That would be a wrong approach though, you should see this show as something to watch without any expectations, just a comfy show to spend half a hour watching after a hard day. It is not a masterpiece, yet there is certain appeal to watching generic isekais.
After all, every isekai is a wish for a better world.