Really, David...

Your one-line pronouncements are tedious. It would be ever so much more interesting if you spent some time developing your theses, perhaps even with a paragraph or two explaining how you arrived at them. It might even stimulate debate - which, last I checked, was still the intent of Habitable Zone.

On this particular topic, I happen to agree that, so far, no properly-conducted investigation has revealed evidence that strange aerial phenomona have other than natural causes (discounting the deliberate hoaxes, of course). However, consider the following:

[1] The nature of heavier-than-air flight itself dictates a hightened awareness of safety. "Objects" in the sky whose presence is not immediately explicable, to either pilots or ground controllers, represent a potential hazard to navigation.

[2] The historical background of WWII and the Cold War created a subtle, but - I believe - still palpable urge among us, who were children then and are now the adult pilots, ground controllers and interested casual observers, to be able to identify anything we see aloft.

[3] Humans are nothing if not curious; we want explanations for things we have not seen before.

All are sufficient reasons to continue to investigate unusual aerial phenomena as they occur and are reported.

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If you'll pardon a semantic nitpick - it seems you have fallen prey to the modern usage of "UFO" to mean "flying saucer" - that is, alleged extraterrestrial spacecraft. You may have noticed that I substituted other phrases equivalent to "unidentified flying object" that do not carry the same baggage. I offer the technique as a way to re-level the playing field in subsequent discussion.