Note: The following is my own speculation, and I have not grounded my assertions in data unless noted otherwise. Read accordingly.
I suspect that a faith in the existence of a force in the universe that cares about you in some personal way--a moral force, a just force, a loving and caring force--is, for many, a basic psychological need. I also suspect that this need is one major catalyst--and continued motivation--for the human phenomenon of religion. Furthermore, as the sciences learn ever more about the nature and origins of the universe, I think that this motivation may be the "last one standing." And, humans being what they are, I doubt that it will ever be toppled.
I also think it is fairly clear that that force, whatever it is, is not nature-- at least, not in the purely physical sense of the word. For every anecdote purporting to demonstrate the innately compassionate character of natural systems, there is one to demonstrate the ruthless and brutal character of the same. Altruism and cooperation may be natural, but so are rape and murder; Jane Goodall may have shown the world the chimps Mel and Spindle, but she also showed them Passion.* Nor can we say that the physical and mental development of any given species demonstrates any particular regard for the survival and happiness of particular individuals. The mortality statistics regarding human childbirth before the development of modern obstetrics, for instance, should put to rest the notion that nature gives a flying fuck about whether a given person survives the very experience that is supposed to bring them into the world.** Natural systems "care" whether a design works well enough to maintain a population at or above replacement rate. Any subsequent casualties are merely collateral damage.
BUT. The above conclusion isn't necessarily easy to come to unless you have some kind of basic familiarity with the natural sciences (and specific cases within them), and a functional (if simple) understanding of how evolution works. Given the current condition of science education (at least within the US), that is a pretty big "if" for most people.
Now. Imagine you are an average person with this psychological need. Then, imagine that you have been functionally convinced, for whatever reason, of the non-existence of God (in whatever form) and/or the destructiveness/irrationality/foolishness of religious institutions. So, religion (in the sense that it is a vehicle for some sort of faith in some sort of God) is out as a way to satisfy your need for a sense of being loved on a cosmic level. Where do you go? Even the most basic understanding of world history will tell you that systems of government, for instance, can't be trusted on a deep level, nor be expected to care for you to the degree that will fulfill your need.
On the surface, especially given the preponderance of anecdotes pushing a vision of it as fundamentally gentle and compassionate, nature seems like a pretty good option. For some reason, (probably cultural, given that the dominant Western religious narratives have been pretty allergic to pantheisms) personifying nature and ascribing benevolent intent to it doesn't initially appear to smack of theism. And since you're locating these qualities within an entity that for all functional intents and purposes can conclusively be demonstrated to exist, I suspect it can pass the initial "sniff test" among those who want to see themselves as rational or science-minded in some way.
Unfortunately--at least from a purely physicalist perspective-- it's also wrong, and wrong premises can lead to wrong conclusions. All too often, I suspect (I have no data to rest this point on, though I'd be interested to know if psychological or sociological data can back my hypothesis up), basing your understanding of how nature works on the premise that nature as such gives a damn about you makes you easy prey for all manner of pseudoscience.
Let's go back to the obstetrics example. If you believe, for instance, that nature cares about you, and that therefore nature "designed" you (as a cis-woman) with a physique perfectly suited to giving birth, you might be likely to eschew hospital birth and obstetric care in favor of homebirth, either unattended or attended by a lay midwife. And you might really believe that this is the safest option. Unfortunately, you'd be wrong. CDC data consistently indicates that homebirth with a lay midwife carries three times the risk of death to the infant as hospital birth attended by a certified nurse midwife, and double that of a hospital birth attended by an OB (the discrepancy between CNM and OB rates is attributable to the fact that OBs see far more high-risk patients that do CNMs.) The linked source, by the way, provides in turn a link to the CDC data, so you can look at the numbers yourself.
So scratching this particular itch with nature as such isn't only inaccurate, it's potentially dangerous. It's also extremely damaging as a whole to the public understanding of science. Which is why I'd like to propose that in some forms, religion may be helpful to science as a whole. If a religious institution doesn't make foundational claims about the nature of the universe such that it puts itself in conflict with the sciences, but rather provides a social space in which a person can believe that there is some kind of a moral order to the universe, generated by a cosmic force that loves them and cares for them, I think that that institution is answering a critical social (and for many people, psychological) need.
This isn't to say that religious belief makes a person immune to pseudoscience or to attributing a compassionate persona to nature-- far from it. I would suggest, however, that if a religious institution functions as I think it ought to-- not as a generator of foundationalist claims, but as a space for fellowship, for openness to this force its participants believe in, and as a moral and spiritual impetus for just, reasoned, and compassionate action (e.g, the American Civil Rights movement)-- then it is capable of functioning for many people as a bulwark against just those sorts of errors.
* Spindle was an adolescent chimpanzee in the Gombe Stream chimp community who "adopted" Mel, an unrelated orphan chimp for several months. Passion, on the other hand, was a high-ranking female in the same community who went on an extended spree of killing and eating the infants of other females for no apparent reason (e.g, food was abundant, the other females hadn't demonstrated any aggression toward her, etc.) Goodall, Through a Window: My Thirty Years With the Chimpanzees of Gombe. Mariner Books, 1990.
** The specious claims of the Natural Childbirth movement notwithstanding.