I think there is a bit of a lack of empathy in your response. First, not everyone has learned how to express affection, especially some of the previous generations. The author even wrote that the father wanted to be involved in his child's life, but did not have practice or models for being the kind of father the author wanted. It does not indicate cowardice. It could be very difficult to switch one's frame of view to something that seems alien. It might have been just as difficult for the author's father to become an affectionate and involved parent, which you see as something he should be able to achieve, as it would be for a typical modern man to accept that plants have the same rights as people, which some future version of humanity might consider to be an obvious given.
Second, people grieve in different ways. Some might engage in self-destructive behavior. Others might fall into a deep depression and have trouble getting out of bed. The father might have found comfort with the routine of work where he could pretend everything was fine. He was at least aware enough to make sure his children were care for, by passing them to the grandmother. He might find seeing his wife or child too much to bear, as they remind him too much of his daughter. There is a reason why couples often separate if a child dies. He might not have the skills to deal with his grief, might not have had help, might not know where to get help, might not have even know he needed help.
Third, there are several different ways of parenting. One of which is what you mentioned, making sure the family has modest needs so that they can live within those means, reducing the burden on the parents to have to constantly strive for ever increasing wages. There are also parents who want to provide as much as possible for their children, the healthiest foods, the best medical care, exposure to many ideas and activities and cultures, which necessitates a tradeoff between effort put into work and direct time with family. It might be easy to agree that the extremes of the spectrum are poor choices, but harder to say where along the middle of the spectrum is the optimum. Which is the main point of the article, whether you agree or not.