Conversely, I'm totally sold on it. The shoulder-hunching thing is so real.

The thing I thought was ergonomic BS was the benefits of columnar/ortho layouts; everyone talked about how your fingers just moved vertically and it was so much better for them, and I rolled my eyes. But dang if it hasn't proved to be meaningfully true for me, too -- when I have to type on a legacy keyboard, I can clearly feel the pain in my fingers. (The disclaimer here is that my fingers are totally screwed up; if you don't feel pain normally, this probably matters less.)