We are both objective and subjective beings. I am suggesting a way to mine that subjective part of our minds for possible insights to what our non-human visitors may be trying to say to us, if anything. For example, if the witness says "It made me re-evaluate our place in the universe," let's take that down and remember it. If someone's life goes through a massive change (moving away from their home, changing jobs, etc.) as a result of their sighting, that's a pretty good indicator that there is much more going on in the interaction than just the sight of a light flitting through the sky or humanoids waving weird metallic objects around.
Although Greg doesn't cite any specific cases, he's probably aware of the lifestyle changes reported by some self-described "abductees," who often emerge from their experiences with a heightened sensitivity to environmental concerns. Is the UFO phenomenon's "purpose" to encourage planetary stewardship?
I'm reminded of Lovelock's Gaia Hypothesis, in which the planet is effectively a single biological entity. Maybe UFOs and their "occupants" are cast members in some vast planetary drama with no actual role other than perpetuating themselves. UFOs and their accompanying entities might be subconsciously reminding us of the potentially apocalyptic burden we bear as an industrial species, all the while encouraging us (via their apparent technological prowess) that we lessen our environmental signature by migrating into space. Such a scenario compliments the "control system" proposed by Jacques Vallee and suggests a link with the collective unconscious explored by Jung (most notably in "Flying Saucers: A Modern Myth of Thing Seen in the Skies").
But where do they come from? If the UFO phenomenon is generated by Earth itself, perhaps it uses the human nervous system as a kind of operating system. Its enduring physicality argues that it can manipulate consciousness in such a way that individuals can function as unwitting projectors. If so, the study of UFOs might eventually lead to a new understanding of the role of awareness. One day, through careful back-engineering of our own minds, we might employ UFO-like abilities through thought alone -- in which case the UFO phenomenon risks becoming obsolete.