Most paintings dont have a cool backstories. They are just paintings. Art student can see technical details of how they were done, but those are not really interesting if you are not trying to learn to paint.
This is basic knowledge.
"Rich people can afford a luxury" is obvious enough, but how rich did you need to be to hire that specific artist? Was Sargent knocking out two portrait a day for every local dentist or was this a one-off where the offer was simply too good to turn down? It'd be cool to know....
And of course, "commissioned by her father, a local merchant" is kind of interesting and it's even more interesting when it's not the case.