@Ironclad: I don't have anything to add in terms of the structure of this story, but I'll just share my own experience on the kind of issue you have.
Essentially you expected the series to go a certain way of your preference and are angry it didn't.
That's fine. I've had it happen to me as well. I profoundly disliked the way Tower of God was going.
So I dropped it around chapter 200, when it finally became clear there was no chance of what I wanted happening.
People have speculated about Arata joining ReLIFE in the end since at least the time when it became clear he and Hishiro were test subjects and would forget each other.
More to the point of your preferred outcome, it became clear there wouldn't be a discussion of office work culture in Japan since like, when Arata visited his senpai's grave. The whole mood of the series has always been learning to move on from a tragic past, not reform the roots of the system involved in the tragedy.
Nobody can fault you for reading to the end nonetheless. Some people like to read stuff to completion for the sake of completion. I certainly translate series I grow to dislike to completion, so I cannot throw stones.
But do you really think it makes any sense to complain about what you knew, or should have known was coming?