When laying out the notes in the two-dimensional [Wicki-Hayden layout](https://en.wikipedia.org/wiki/Wicki-Hayden_note_layout), which is the most symmetrical layout I know of, it is visually clear that D is the "most central" note.

Why, then, doesn't D play a central role in music theory? Or does it? And similarly for the related [Dorian scale](https://en.wikipedia.org/wiki/Dorian_mode).