When I posed the question "why?", I wasn't trying to make it out that McCoy was baffled by the notion of a doomsday machine, but somehow 60's audiences weren't. I was suggesting that, unlike the 1960's in which TOS was made, we now live in a world where horrific things happen and people have, to a degree, stopped asking "why?" to try to understand the motivation behind the latest bad news.
That's one of the things that makes the 1960's a world apart from today, and it looks to me like we lost something more than just our perceived "innocence".
I'm wondering, were you around in the '60s and '70s? The '60s were a bit before my time, but I know from growing up in the '70s and '80s that people were living under the constant fear of nuclear annihilation. People today think that the fear of terrorists blowing up a plane or a building is horrific, but back then, it would've paled next to the everyday fear of the end of the entire world. So I just find it rather disingenuous to claim that people back then had some kind of innocence that's now been lost. If anything, the present is a more innocent time, because the world is so much further from the brink of immediate doom that our definitions of what constitutes a "horrific thing" are much smaller in scale.
It's the nature of human memory that negative experiences are stored less effectively than positive ones, or that we simply try not to dwell on them as much. So over time, the bad things in the past fade in our recollection, and it creates the pervasive illusion that the past was better or purer or simpler than the present. But that's a myth people have been believing for thousands of years, and it's no more likely to be true today than it was at any time in the past.
. . . here was a prime-time network hourlong drama that, with very few exceptions, stuck to a genuinely G-rated vocabulary for whole episodes. If I'm not mistaken, you could go months on end and hear no profanity from any of the characters. Proof positive they really don't make 'em like they used to!
TV censorship was a whole lot stricter back then. In fact, the only “profanity” (if you can call it that) in all of TOS was when Kirk uttered the famous line “Let's get the hell out of here” at the end of “City on the Edge of Forever.” And it was a bit of a battle with network censors to keep that in.
Although it was allowable to use "hell" and "damn" in a literal sense or in a standard expression rather than as expletives: Decker in "The Doomsday Machine" said the planet-killer was like a devil "right out of hell"; McCoy in "Spectre of the Gun" described Tombstone as "hell-for-leather, right out of history"; and in "Court-martial," Kirk said the computer log's evidence against him was "damning."
They did employ milder oaths, of course: "blast it," "What the Devil," "What in blazes," "What in heaven," etc.
When Marvel Comics got the Trek license in the '90s, they apparently were trying to be accessible to a young audience, since they tended to avoid profanity there; but they did it by having the characters say "heck" and "darn" and it came off rather silly. It would've been better if they'd used the same mild oaths employed on TOS.
Two words: Belly buttons!
Actually that's not so much a quality of the '60s. Network censorship at the time was so strict it forbade showing the female navel. Evidently that policy had relaxed by 1968, though, judging from the shots there (though Palamas' navel is hidden, as one would expect from the early second season).