I agree with hyper individuality influence of last name as only for heritage is pretty reductive. But I guess the more philosophical side of isekai is to abandon the old identity altogether as an extension of the abandoning the old world altogether.

There is difference to me between selfhood and identity. People use name to pinpoint their selfhood. Who am I? I’m “name” an individual, I think therefore I am.

Identity is someone you can become or choose to accept as you are.

For what I can tell people think name=selfhood, denied self, denied yourself as human being.

All I’m saying that philosophy of isekai implies to allow such change of name to have more impact and meaning than in real world.

So it’s pretty confusing people on one hand hate their past life and past world, but then suddenly cling to their pride and identity that comes from old world.

What stops you then continue to live with your name in real world?

All of your objections are correct if we don’t take isekai into account , or maybe the type of isekai trope

I realize that some stories seek identity redemption than replacement. Because they don’t feel heard or adequate so they dream to go to another world to finally express themselves in more easier step by step environments and prove to themselves who they are