If you’re really excited about the OMM aspect of DO schools, talk about why osteopathic medicine. Otherwise, just talk about why medicine. Your PS should have that genuine feel to it, and if you couldn’t care less about the osteopathic part of osteopathic medicine, it will likely come through in your words.
I only talked about "why medicine". Left the "why osteopathic medicine" to the secondary questions....almost every DO school will have some sort of prompt asking you to explain why you're applying to a DO school.