Never assume any child will willingly wear a hat. In my experience, the more love and creativity that has gone into it, the more likely that the child will treat it with complete disdain if not utter disgust.
I don't knit. I didn't knit for dcs and I certainly don't knit for dgd. So far she has managed to reject a positive wardrobe's worth of headgear. As did her father. Unfortunately, my former MIL took this as a personal insult to her beautifully knitted garments. Sometimes I doubt she has forgiven him.
PS. Did nobody think of the children having to pose in those fishy hats? Their lack of enthusiasm is almost commendable.