Well, I'm not one who disparages Miles' chops; I think you are on to something real when you say "He didn't choose to play that way all the time". . . (to paraphrase your phrase).
I believe that Coltrane was a presence that caused Miles to react in a different way than he did with Stitt, or Mobley, or Shorter, or Grossman, or Leibman, or. . . . I think Miles tailored his playing to the music and the musicians he was playing with in a more studied way than many/most of his contemporaries.
Of course, that's just my personal thoughts from a three decade listening experience. . . .