When New York Times film critic Manohla Dargis screamed from atop the poster that Azazel Jacobs' Momma's Man was "independent film defined", who knew what a scarily accurate harbinger this would prove to be?

In the four years since, the Apatow model of male arrested development has singularly defined much of the US independent sector, a rot that started innocently enough with the Zach Braff breakout Garden State almost a decade ago.

Indie film and the kinds of filmmakers that Sundance championed in its nineties heyday were dangerous, radical, and unpredictable; Quentin Tarantino's Reservoir Dogs, Gregg Araki's The Doom Generation and Todd Haynes' Safe immediately spring to mind. But where once the festival was about forging a passionate connection to new voices with fresh perspectives, on the evidence of depressingly familiar man-child comedies in its more recent history, the Sundance of today is as much a formula factory, experimenting with different combinations of the same elements for potential crossover hits.

The poster child of arrested development?

The risqué, take-you-to-the-edge characters of the last century have largely been supplanted by hypersensitive, utterly resigned, directionless whiners, burdened with the apocalyptic responsibilities of adulthood. In some extreme cases, even a beautiful, devoted girlfriend (Braff again in The Last Kiss) isn't enough to shake the malaise of the fast-approaching thirties. What these sad sacks really need is an intervention in the form of a completely unobtainable fantasy girl who exists solely to make depressed men learn to love life again with their delightful quirkiness. These manic pixie dream girls have no agenda of their own other than helping the male protagonist realize their mistakes as the credits roll, setting them on the path to achieving what they should have done a decade earlier whilst they were busy moping around.

To cite just a few examples from across the spectrum, Greenberg, The Science of Sleep, Happythankyoumoreplease and Two Lovers are all guilty of similar acts of emasculation, replacing sharp-tongued, resolute confidence for morbidly shy, socially anxious rejection, any speck of confidence usually lacking the facts to back it up. I might count myself amongst the deluded and disillusioned, but there's only so long I can go on cheering them. Right now it seems as though US indie films are completely disinterested in offering cooler alternatives to aspire to when playing the world's smallest violin comes so easy.

The stronghold this archetype currently holds on US indie film is so pervasive and odious, the stench has even retroactively tainted some of my favourite low-budget odes to the difficulties of growing up and moving on, including Kicking and Screaming, Beautiful Girls and Chuck & Buck. These days, the coupling of the Fox Searchlight logo and the lobotomised poker face of a despairing lead in the first five seconds of a trailer are enough to make me leave the cinema for a quick, life-affirming stroll around the lobby (careful to avert my eyes from all the posters advertising blockbusters, remakes and sequels).

This desperate pining for youth and a time when dreams didn't seem so desperately out of reach has recently exploded, even on fringes beyond the reach of the multiplex, thanks in large part to the increasingly raised profile of New York's mumblecore scene. These awkward fumblings go as far back as originator Andrew Bujalski's Funny Ha Ha and more recent entries such as Aaron Katz's Cold Weather and Lena Dunham's Tiny Furniture. Many of these hipsters are now slowly transitioning into the mainstream – Lena Dunham's contemporary Ry-Russo-Young was there in person at Sundance London plugging their co-scripted Nobody Walks, which looks for all the world like a polished studio product, carrying no trace of the low-fi world in which she rose to prominence.

The trend shows no sign of slowing either, with upcoming releases once more throwing an emotionally stunted spotlight across all strata of US output; indie (Nancy, Please), indiewood (Jeff Who Lives at Home) and mainstream (The Five Year Engagement). The developmentally challenged man-child is here to stay ladies and gentlemen and by whatever means necessary, orally, rectally, intravenously, intranasally – I don't care which – this sad, monotonous state of affairs needs to be addressed.

Which brings us, after a fairly lengthy rant, to Colin Trevorrow's much buzzed-about time travel comedy Safety Not Guaranteed, the film that all critics not yet thirty at Sundance London were most excited about seeing. Despite the high concept, Derek Connolly's debut script is typically Sundance; a depressive character study incidentally careening around in much the same way as those it profiles. The secondary stab at sci-fi is a bums-on-seats ruse, content to nostalgically sigh for the past rather than boldly explore it.

Excessive quirkiness, interrupted by a couple of scenes of confessional drama, is a combination that goes down easy for most, but even with lowered expectations, the slot A, tab B plotting doesn't have much traction beyond the real-life ad that inspired it, struggling to hold interest in the second act and floundering when it's required to flesh out extraneous characters.

Smugger-than-thou journalist Jeff (Jake Johnson) drags two slacker interns along with him to investigate the author of a nutso classified ad: "WANTED: Somebody to go back in time with me. This is not a joke. You'll get paid after we get back. Must bring your own weapons. Safety not guaranteed. I have only done this once before."

From the moment this motley crew assembles the comedic dialogue is offensively eager to please and desperately clichéd in its attempts to do so. "Get in retards", Johnson's not-at-all-lovable douche cries as he rolls up in his obnoxious fuel guzzler.

Can we please, please put a moratorium on outspoken characters ignorantly using the word retard? Contractually obligated in just about every smart-alec indie, it's beyond played out at this point and was never smart, cool, funny – or as this film would have us believe – remotely endearing in the first place. In less than a second, one of your already seriously unlikable major characters now has to work doubly hard to get on my side and win any sympathy. Well played, Trevorrow.

Jeff is there to pick up virginal Indian nerd Arnau (Karan Soni) and the Manga-eyed, quip-ready Darius (Aubrey Plaza). Plaza, who scowled so memorably in Whit Stillman's comeback Damsels in Distress, is a spiky blend of Scott Pilgrim and MTV's Daria here – the actress was in the former and her questionably named character is inspired by much more than the latter's moniker.

Karen Soni fares a lot worse as the clueless, ethnic virgin who's there to be mocked and laughed at, rarely offering anything beyond appalled reaction shots to "go big or go home" American insensitivity as a voiceless foil for Jeff. Swapping the black comedy sidekick for a brown one and adjusting the volume doesn't help make Arnau any less one-dimensional. That Arnau's whole plot function revolves around living out Jeff's bygone past is an indication of how much Connolly's script struggles with its secondary characters, whom are neither convincing or compelling.

Jeff, the self-purported lady-killer is in fact disgusting. Driving out to Washington under false pretences, Jeff has no interest in the story and every intent of the interns doing his work for him while he tracks down a high school blowjob (I'm telling you this guy is charm personified). An utterly half-arsed attempt at befriending time-travelling Kenneth fails immediately, handily allocating Darius the task of gaining the eccentric kook's trust. Meanwhile, Jeff, seeing his old flame again after all these years, is appalled by her "fatness" which in no way resembles the air-brushed stick thin FHM models he'd like to believe he's used to dating. Yet ninety minutes later, because the plot demands that his character arc must dovetail neatly with the main action of the Darius/Kenneth relationship (and even in this respect it's severely confused) all misogyny is apparently forgiven because this woman is actually the love of his life, who it turns out, 'isn't quite as fat' as he first thought. He does a good line in sex jokes though, more than enough for less discerning audience members to overlook his complete lack of values as a human being and take him into their hearts.

Despite its unfortunate penchant for gross caricature, the comic choreography of the central relationship (in both montage and unblinking stare-downs) is ultimately winning. The offbeat staging of a supermarket meet-cute between Darius and Kenneth is impeccably droll, the urgently whispered delivery having great fun at the expense of John Keel era paranoia. Initially hiding behind their swagger, they soon come to realize how much they have in common, both with loved ones in their past they wish they could go back and save. Plaza perfectly judges when to expose the vulnerability behind the snark and Duplass (a man-child vet having co-directed Cyrus) makes for a surprisingly affecting oddball. Trevorrow mishandles the is-he-crazy-or-telling-the-truth tension, but Duplass' straight-laced commitment to Kenneth's conspiracy panic is so believable we buy into the threat of the pursing men in black even as they prove laughably ineffectual. With all his talk of the "action getting hungry" and the "heat getting hot" when Kenneth does finally "breach the perimeter" of a laboratory containing essential parts for his time machine, the monumental hubris of his sober action-film line readings is gloriously sent up as he flees a late-night office party. Where Trevorrow so easily could have looked down his nose and ridiculed, he steps back and lets Duplass find the humour and heartbreak in Kenneth's overestimation of his own competence.

Though Darius is granted some measure of agency and aspiration, it always feels as though she's the eyes into Kenneth's story. What's presented as an equal relationship of both mutual respect and converging plot points is ultimately one in which she assumes the MPDG role, helping Kenneth move on in some way and assuring him he did a good job even when he was misguided. In true manic pixie dream girl fashion, she's also not at all age appropriate and way hotter than he deserves.

Even when they have each other, this isn't enough for Darius and Kenneth to leave the past well alone and live their lives in the now. Depressingly, the ephemeral fixation persists, obsessive nostalgia mistaken for hope, co-dependency appropriating friendship, dogmatic self-belief muddled up with delusions of grandeur. Joe Landauer and Franklin Peterson's editing, combined with Ryan Miller's musical score ends the film on a false note of optimism, so perfectly constructed it still manages to inspire awe and wonder. Nevertheless, it's hard not to leave the cinema with a heavy heart.

This exclusive interview with Safety Not Guaranteed director Colin Trevorrow was conducted by Timothy E. RAW at the 2012 Sundance London Film Festival.