Hi, not the dev but the composer, for reference (my views don't represent those of my commissioner etc) but I wanted to respond to this.
I didn't write it but I can guarantee this game wasn't written as political commentary. Most of the conflicts in the game are on the individual character level. I don't think the story was intended to be read as being about the importance of the status quo, but about optimism vs. pessimism rather than "right vs. wrong/agree to disagree". I understand how you could read it that way if you were searching for a game to comment on the current climate and came in expecting that, but I feel like somewhere along the line your expectation of what the game should be saying about the world became more important to you than what the game actually said.
The two worlds don't represent political views but attitudes toward life and problem-solving. I don't think the two worlds were ever meant to represent an us vs. them. You even say here: "all conflicts are personal or horizontal". I believe this is intentional because the question isn't "who is right or wrong in this power difference" but more "what is the right way to feel and handle when presented with a complex problem". The message isn't meant to be that arguments should meet in the middle, I feel like it's meant to be that both optimism and pessimism are necessary for solving problems; it's about the base level emotional response to a problem rather than the moral question. I'm sorry the game didn't provide the deep political commentary you wanted but I also think you're likely reading a bit too much into it expecting it to comment on something it isn't trying to. It was written half a decade ago and I'll be honest, nobody expected the fascist political climate we have right now back then. (I don't think if I were to have written a game back then I could have commented on today's environment either!) But I guarantee you nobody who worked on this game thinks fascism is ok or that the solution is meeting in the middle. Speaking for myself as an lgbt individual I can guarantee you I am not meeting in the middle with fascists. :\
But I do think if you're reading into the power dynamics of a sentient cardboard box or ear of corn, you may be thinking about it a little too hard... A lot of people see the worlds of joy/sorrow as representing good/bad but I think it's more meant to represent blissful ignorance and depression respectively. I feel as though your review is more about what the game isn't/doesn't do than what it does do which is a bit difficult to comment on.