My name is Paul, I write from Canada. You see the good posture as a measure to prevent playing-related neuromuscular disorders. I see issue of posture reiterated to every student at almost every lesson, and it's been so for centuries, and the more so since 1980. But I also read the research (by A. Brandfonbrenner) which showed that 9 out of each 10 piano students suffer playing-related pain in their hands in the first years of learning - and it's the research from 2009.
Do you believe that so many hopefuls are hurting because all of them - and their teachers - neglected the posture? How do you see it?