Regarding saddles, the basic rules note:
Saddles. A military saddle braces the rider, helping you keep your seat on an active mount in battle. It gives you advantage on any check you make to remain mounted. An exotic saddle is required for riding any aquatic or flying mount.
As a comment to this question, one commenter wrote those statements to mean that saddles are required for flying mounts. Another commenter wrote that his interpretation is that saddles are not required for flying mounts - exotic saddles only confer advantage when used.
Are saddles required for flying mounts? Has this been clarified anywhere else in rules, adventures, or comments by the game designers?