It's quite true that Gilliard spoke highly of Olga's charm, intellect, and her potential. However, many of Olga's admirers tend to overlook this additonal observation from Gilliard's memoirs:
"Olga Nicolaievna did not fulfil the hopes I had set upon her. Her fine intellect failed to find the elements necessary to its development. Instead of making progress she began to go back."
In a different environment, I agree that Olga might have been capable of great things. As a royal, however, I think her prospects were limited by her time, place, and station.