Even with all that, Adams keeps things moving with an impeccable sense of pace and flexibility that's allowed the series to be adapted to every narrative medium you can think. Besides the original radio plays, there are, of course, the novels, but also the BBC TV adaptation and the 2005 movie, numerous theatrical productions, the adventure game Adams scripted himself (my first exposure to this work), the radio plays based on the novels that weren't radio plays to start with... and of course, at least one official towel. Through all of them, the lines have remained quotable and the twists memorable... so memorable, in fact, that we tend to forget just how heartbreaking and sad they can be.
To some degree, I think it's clearest in the stories' original form, the BBC radio plays, which I recommend every Adams fan hear, no matter what their favorite of the series may be - thankfully, they're available for download and streaming on Archive.org. Not to say that these are their definitive best form (they all have their own merits), but there is something special about hearing the text, much of which fans know word-for-word, coming from the mouths they were originally written for. But there's also something of the era conveyed, too, a tone shared with other British works of the time, a sense that the idealism and openness of the sixties and early seventies had gone, and that there was something cold and mean on the horizon. (Adams, of course, was friends with David Gilmour of Pink Floyd, whose Animals album came out a year before the premier of Hitchhiker's and conveys this feeling perfectly.) By the time the series premiered, the days when Adams could lie in an field (just drunk enough to experience "a mild inability to stand up," as he put it) look up at the starts and imagine the phrase "hitch-hiker's guide to the galaxy" have seemed very off, since he starts the series with the literal destruction of a safe, comfortable space by hard, mechanized modernity (Arthur's house being torn down to make way for a highway bypass) and immediately follows it up with the destruction of all of humanity's space, comfortable or otherwise (the destruction of the Earth to make way for a hyperspace bypass). And this is only the first episode! This quality is present not only in the series opening, but remains a constant throughout.
The Hitchhiker's Guide to the Galaxy, in all its incarnations and installments, exists in a time and space that could be described as "the moment after" (regardless of which of the many, many spaces and times the stories are set in). If anything, the dual destructions Arthur Dent endures are unusual because he (and thus the audience) is present for it, but, even here, the events are the result of choices and mistakes made long before: by the Planning Board, by superinelligent shades of the color blue, by the beings that appear as mice, by the ancient supercomputer Deep Thought, by Slartibartfast and the other Magratheans... Essentially everything in the series is like this, usually beyond the characters' understanding: the good (or at least better) times are over (or ending) and we've missed them... all that's left is the fallout. It's the end of the party, shame we weren't there - which is literal in Life, the Universe, and Everything, where the Longest-Running Party in History finally stops when our characters arrive. We see Grand Plans and potentials fall away time and again, the collapse of civilization after civilization, tragedies colossal and infinitesimal (sometimes, Adams being Adams, simultaneously)... we'd be crying if we weren't laughing so hard at the absurdity of it all.
Adams's principal tool in making this paradoxical combination work is distance. The clue is in the franchise title and the way that the omnipresent narrator is credited as "the voice of the Book" (i.e., the titular Guide). This allows him to be as summary or detailed as he wants to be without breaking the flow of the action, conveying the feeling of jumping between encyclopedia articles and predating the concept of a "Wikihole" by decades. If, as the saying goes, one death is a tragedy and a million deaths a statistic, either can be a joke if brought about by absurd circumstance and viewed from far enough away. This very long view also makes possible another Adams hallmark: the lack of villains. Stories told up close often have to rely on characters that knowingly do bad things for the central conflict to take place, but this isn't as necessary when they're about chains of events separated by light years and centuries. And so the conflicts and tragedies are almost always the results of misunderstandings and carelessness, rather than active maliciousness. (Mostly Harmless, the final novel, is something of an outlier here, as it is in a number of other ways that Adams himself was ultimately dissatisfied with.) This is made particularly clear early on, when one of Arthur's litany of grumblings, something of a necessity when writing for audio, leads to events far more catastrophic than his own, namely the destruction of multiple civilizations and most of a galaxy. (The text adventure brilliantly recreates this scene using a previous instance the player has entered a command the game is unable to parse. Since this was my initial exposure to Hitchhiker's, I first got to experience it with the phrase "hang gown on hoo," a typo that will haunt me to my dying day.) In the text following this passage, we're told that "this sort of thing happens all the time," and, true to his word, Adams shows it to us time and again over the course of the series.
So what, then, is the alternative? Arthur bounces along from place to place, unable to ever really understand anything going on around him, making him an ideal audience stand-in, but also unable to ever address the traumas he's experienced. Ford, particularly in the early in his earliest portrayals, is a burnout, forever chasing the novelty of experience, ultimately becoming increasingly unhinged in the process. Zaphod is a narcissistic opportunist, getting through situations by centering them around his own ego and what personally benefits him. Trillian is, sad to say, barely a character at all, existing primarily for others to interact with. And that leaves Marvin, butt of joke after joke, a comic character based solely around a single personality trait. And yet... with his oft-mentioned "brain the size of a planet," Marvin is the only one who always understands everything going on around him, who is privy to all the secret history of the universe Adams/the narrator/the book is sharing with us. He certainly isn't dealing with the universe in a healthy way, but at least he is aware of it and acknowledges it. The Original Paranoid Android may have been a far hoopier frood than we ever realized.
But giving us a clear direction would have defeated the purpose of the whole thing - Adams wants us to find out our own way through, while reminding us not to panic. He shows us the universe and fills in the background, but we're all hitch-hiking our way through life in our own way. And, as we see our own dark futures on the horizon, we can be thankful for what he left us: a confused mess of terrible events, unanswered questions, and the all the hilarious moments we experience in the face of these things. Sounds just like life... not to mention the universe, and everything.