Emilia, thanks for conveying how intrusive, directive, awkward and inappropriate it is for others to ask you to smile. But I do have some qualms about your very first point.

Why would anyone want to get involved in my facial expressions? Because an intrinsic part of facial expressions is social communication. Your emotions are yours, triggered by cues your brain is responding to, and you are the one feeling your feelings, but the facial expression aspect of an emotion seems to primarily exist in order to communicate with others. So in that weird way, since we are social animals, your smile (or lack thereof) isn't just your smile, it is a smile for the whole community. It's part of why genuine smiles can be contagious.

Maybe instead of triggering a wave of negative emotions (point 4), and even with the validity of all your other points, you can train your brain to have a new response. Something along the lines of "that social animal over there is perceiving that I am to some degree unhappy, and even if they don't know why, and are doing it crudely, they are trying to show me both that they care, and that they hope for me to be happier. That might create a flash of joy or connection, even if you then chose to return to the thoughts and feelings that contributed to your sadness or other negative emotions.

And my sincere apologies if this feels like a recurrence of directive, intrusive, inappropriate commentary.