The hypotheses of intelligent design, as well as the related hypothesis of "directed evolution," have been a matter of speculation for quite a long time in the realm of science fiction. In fact, the two ideas are often referred to as the "black monolith theory" after Arthur C. Clarke's 2001, A Space Odyssey, where creatures who look like black monoliths tamper with ape evolution to make smarter apes, i.e. humans.
Intelligent Design advocates are obviously squeamish about inquiring into either the design process or the motives of the designer(s), owing to their religious intentions. They deny that they are actually Creationists, but silence can speak louder than argument. The refusal to address important issues speaks volumes. Fortunately, science fiction writers and readers are not so shy.
In science fiction, the motives of the alien meddlers have long been a matter for speculation (and some cracking good yarns). I'll summarize a few of those ideas here. I will henceforth call the meddling aliens "black monoliths" or simply "monoliths." One hypothesis is that of "Benevolent Education," namely that the monoliths might be lonely, or otherwise desiring of companionship, so they try to create said companionship and do so benevolently, as parents might raise children. At first glance, this might seem to give a special place for humanity in the general scheme of things, and indeed, often that is the case, in such stories. There are, however, other stories whose authors have a greater sense of the ironic. In some of those, it turns out that humanity is merely a byproduct of a plan for some other creature (e.g. "God must love beetles; why else would he make so many of them?"). In other stories, humans are still a very primitive form, and it will still be billions of years before the process produces anything actually interesting to the black monoliths.
A related, and also darker, vision is one in which what the monoliths desire is not companionship, but rather servants, or maybe slaves. In some versions, humanity is too cantankerous to make good slaves. In "happy ending" versions, this leads to either being left alone or a war in which humanity prevails. In more realistic versions, the monoliths just wipe us out and start over.
There is at least one story in which we have not been made slaves because we just aren't smart enough yet.
In various stories, the motive of the monoliths is simply esthetic. The world is made because the monoliths find it pleasing. Sometimes this is of little comfort, since tastes can change, and who knows what next year's fashion brings?
Feel free to add to this list.