The author of the article correctly notes that as the universe does not itself have desires and is not cognizant, the world has no ultimate purpose (and even if a god created us for or with a purpose, that is not mean we are bound by that purpose or that it is a purpose that would satisfy us.
Early in the article, though, he asks a very non-rhetorical question that I think should and can be answered:
I do not know where this want for an external purpose comes from. Perhaps it is some left-over brain program from our childhood where we are inclined to prefer the values of our parents. Perhaps it is something that is taught from one generation to the next without stopping to consider the wisdom (or foolishness) of doing so.
Fyfe cannot identify with the search for an external, larger, purpose to life, or the emptiness many can feel when they do not find one. While I can relate - I have no need to find a 'bigger' purpose - I can certainly relate to those who do and think I can give some explanations here. And a search for a 'bigger' purpose has little to do with motivations that Fyfe proposes.
Why do we search for grand purpose in life rather than being satisfied with human-made purposes? First, I believe that we do this because many lives that contain hardship are assuaged by the belief that "there has to be more than just this." Slavery is a good example of this. The slave, who was/is forced to toil for many hours a day under brutal condition, and who had no control over his/her life, may take comfort in the idea that he/she is part of something larger and better than his/her own day-to-day. Saying that the slave's own life is the purpose of his/her life does not do becuase he/she feels their life to be intrinsically purposeless.
But what about those who are better off? Why do folk with relatively happy (or at least very tolerable) lives feel the need to search for a larger purpose? I have known many who've done this - who go into a particular profesion, for instance, because they feel they are "serving the greater good," or the like. Even if they are creating this purpose for themselves (which often they have), they are comforted by the fact that they are serving a purpose larger than themselves, and would be unsatisfied with the suggestion that they have created, rather than been given, a purpoose for their lives.
In these cases, having a purpose imposed on one (or the feeling of it) makes the purpose feel more real and legitimate. It does not feel self-serving, but other-serving. Teh best analogy I can think of is the satisfaction of scoring well on a test of someone else's creation versus scoring well on a test that one whore oneself. The latter does not cause satisfaction because the task was too easy, as one simply gave the answers to questions one created. The real satisfaction lies in beating the challenge of performing well under conditions not of one's own making.
In the same way, creating one's own purpose to live up to is less satisfying, because less challenging, than fulfilling a life purpose created by onesself.
Another reason why serving a "larger" purpose is seen as more fulfilling than serving one's own individually made purpose is because when serving others, one can feel like they are making a difference in the worldd, rather than just in themselves. This is seen by the familiar film and book plot/theme of the shallow business person (or other type of egoist) that lives like solely for themselves but unexpectedly finds joy in helping others (which was, generally at first, against his will). [films like "Family Man" or "Two Weeks Notice" are more popular examples.]
I have never really felt the need to seek after an externally imposed, and larger, purpose. But I have felt the need to help others rather than pursue solely what is in my own personal interest. I did this when I became a teacher rather than went into a PhD program. I wanted to do the latter, but did the former because I wanted to do something at once hard, helpful, and effectual. All I can say is that this choice, while certainly the tougher path, felt more "solid" than the self-serving goal of PhD because it involved helping others by making a sacrifice. While I was not searching for a higher purpose, I can attest to the psychological pull that serving social (and in some sense, larger) purposes can have over serving individually made (and smaller, by radius) purposes.