The longtime leader of Dr. Seuss Enterprises discusses the responsibility that comes with managing the valuable vault of books and IP left by the author and illustrator of such indelible children’s books as “The Cat in the Hat,” “Green Eggs and Ham” and “Horton Hears a Who.” She details the company’s approach to expanding with content beyond the original Seuss canon, and she outlines the reasoning behind the recent flurry of new Suess-related movies, TV shows and books.