just that in this one moment, they did something good for their kid
We don't even know that. For all we know, the kid hates Pokemon but the parents thought their costume idea was too cute to skip. To your point, this photo shows exactly what the viewer projects into it, and that is not necessarily good parenting.
(Also, that's not how most photos exist. Context is supremely important to most photography, because otherwise that photo of Thích Quảng Đức is just an album cover that goes hard.)