Gaudet is skeptical of the importance of ensuring children learn to read early. She offers various anecdotes about the development of the culture of reading in America, starting with the promotion of reading for religious purposes in the seventeenth century (not-so-coincidentally, her area of expertise is reading in early America), with the implication that since the real purpose of promoting reading back then was religious, the promotion of reading today is somehow suspect.
She comments, "I went to graduate school with a plan of studying the use of literature in schools, but my PhD program found that topic embarrassingly pedestrian, so I studied the use of literature in early America instead." Perhaps, had she been permitted to study the educational side of things, she'd have learned why it is people seem to think that it's important for children to begin reading early. Children probably learn a large fraction of their vocabulary through reading.1 And the gap in vocabulary between low- and high-performing students grows as they do.2 So it is, in fact, important to encourage children to read more, earlier.
Is reading a "moral good" in the sense that those who are skilled at reading are morally better than those who are not? Of course not. But it is a practical good, and on average, those who are skilled at reading will find greater success in life than those who are not. That's reason enough for parents to encourage their children to read, surely.
Gaudet's handwringing about teaching children to read being an unequal burden on the disadvantaged is basically meaningless. Pretty much everything is an unequal burden on the disadvantaged. But is it more likely that the solution to that is to aid the disadvantaged, or for the privileged to abdicate responsibility for teaching their children to read out of solidarity?