This book would be much better (although still probably not an amazing book) if Donkey-Donkey found his own inner strength at the end in accepting his ears the way they were at the beginning. Maybe even found some benefit to holding them that way, or their length, instead of just finding problems with every other way and defaulting to the original because 'that's what donkeys do.' Or maybe he could have found some crazy way of holding his ears that nobody else did, and become a local attraction. I don't know.
Message
Rely on others to validate your self-worth.