I think the way it worked at TSR in the late '80s was that
(1) People way up at the top came up with a list of product concepts. Maybe they consulted various departments, or maybe not.
(2) They pitched this list to Random House (distributor of TSR products to the book trade), and then adjusted according to the response.
(3) They told the department heads, "This is what we're going to do". There might be considerable room to define just what kind of content would lie behind the cover of a book with such-and-such a title, but it was on the release schedule.
(1) People way up at the top came up with a list of product concepts. Maybe they consulted various departments, or maybe not.
(2) They pitched this list to Random House (distributor of TSR products to the book trade), and then adjusted according to the response.
(3) They told the department heads, "This is what we're going to do". There might be considerable room to define just what kind of content would lie behind the cover of a book with such-and-such a title, but it was on the release schedule.