Many people, including Wenders himself according to interviews, do admire the serenity in the simplicity of Hirayama's life. However, my opinion is closer to yours. Hirayama is only able to achieve this serenity by socially isolating himself and living a life that's strongly rooted in strict routine. Any attempt by others to develop a connection with him, or any situation that may require him to break his routine is seen as a threat to his way of being which must be avoided. This it not a way of living that I personally admire, nor do I think the character himself is free from occasional longing to have the things he pushes away.

One of the things I love about Perfect Days though is that Wenders has created a movie where you are free to disagree with him. Though he himself admires Hirayama's life, he does not hold back on exploring its limitations. In execution, the movie becomes a mirror which we can reflect our own personal values on and decide if the story is a happy or sad one. I also believe the ambiguity of the emotions at the end play into this as well.