All human situations have their inconveniences. We feel those of the present but neither see nor feel those of the future; and hence we often make troublesome changes without amendment, and frequently for the worse.
What makes "The Monkey's Paw" seem particularly frightening is that it is based on a truth about reality. Most of us have had the experience of wanting something (which is similar to wishing for something) and then being disappointed or worse than disappointed when we got it. A wish can affect one's entire life if it is fulfilled--and many wishes do get fulfilled because people take steps to fulfill them. As Franklin says: "...we often make troublesome changes without amendment and frequently for the worse." Such changes could include getting a divorce, getting married, changing jobs, moving to a different city, buying a boat, buying an airplane, even buying a house. Many people get into credit slavery through fulfilling wishes. Some good examples in literature of people being disillusioned when their wishes are fulfilled are Pip and Macbeth. A good example in real life is Bernard Madoff, sentenced to 150 years in prison (see third reference link below).
One avenue of examination for the story is to look at the questions surrounding fate and destiny that W.W. Jacobs examines in his most popular story. The idea that the Whites end up sacrificing something they really love dearly, their son, in order to get a couple hundred pounds to pay off their mortgage presents an interesting question about wants and needs and the possible consequences of our desires. Of course no one ever wants to lose a child in order to get money, but it does raise the question about our willingness to make certain sacrifices without considering the consequences.
Another avenue of examination for the story is a structural one, looking at how Jacobs structures his stories or his delving into what is called "black humor" and darker stories.