Well, in Roessler's coffee-table book, the story is told (p. 78 ff.) that the wife of the then business manager of the company was a designer, who brought sketches of the microphone to Wilhelm Braun-Feldweg, professor of design at the then Hochschule der Künste (College of Fine Arts, which has since become a University) in Berlin. He is said to have proposed some "final details" about what the book's English translator calls "the width of the edges and the bridge of the basket" ("der noch kleine Details an der Breite der Ränder und am Steg des Korbs ändert"). It's implied that a conical housing tube and the general design of the head basket had already been decided upon--though Roessler is adept at letting the reader infer things without his ever saying them, and that can sometimes conceal a truth or two.
It makes sense to me, though I have no concrete evidence, that Stephen Temmer's association with the company had raised their awareness of marketing and visual design considerations. Again the book attributes his influence to the fact that the microphone was issued publicly as the "U 67" rather than "U 60" as originally intended, and as the initial batch had been labeled. This broke Neumann's postwar pattern of naming new microphone types after the year of their planned introduction, and was meant to strengthen psychological associations with the U 47, which the new microphone was intended to replace.
