Speaking of the pre-director's cut Donnie Darko, critic J.E. Barnes offers one of the best explanations of how Richard Kelly hurt his own movie:
[T]he revision, however more closely it may dovetail with Kelly's personal vision, considerably dilutes the film's drama and power on almost every level. While the theatrical release was fueled by its own judicious editing, structural hard edges, glorious ambiguities, and evocation of the suburban weird, the so-called director's cut continually literalizes the plot while simultaneously altering the status of essential story elements.
In a grave error of judgement, the daimonic rabbit Frank, a dominant presence in and the very symbol of the theatrical release, is now overshadowed by Roberta Sparrow's previously obscure book, The Philosophy of Time Travel, which is brazenly promoted into the foreground. Additional superfluous scenes of the Darko family interacting (which were wisely included as outtakes only in the original DVD) undercut the film's pivotal forward momentum, while the deletion of some of the mean-spirited dialogue Donnie's peers direct towards one another weakens the satiric and parodic humor of the original.
Key characters, like the free thinking, anti-establishment teacher beautifully portrayed by Drew Barrymore, now seem to have briefly wandered in from another film entirely. Awash in new CGI effects, the director's cut should make more logical sense, but simply does not. The film's last ten minutes, in which everything that has gone before coalesces into terrible meaning, should have been considered sacrosanct and left unaltered. As a result of these changes and others, a clever, multi-faceted, fairly original, and genuinely tragic film has become a muddy, unfocused, and protracted exercise in the unthreatening and the banal.
So in a reversal of several well documented Orson Welles projects, including The Magnificent Ambersons (1942)... Donnie Darko: The Director's Cut is a concrete example in which the much-maligned Hollywood executive machine has actually strengthened a creative work through forcible tampering.
Saw Donnie in a mostly empty NYC movie theatre during its brief, original run a few weeks after the World Trade Center attacks. The jet engine crashing through the suburban ceiling had a cosmic message ("temporal loops happen") as opposed to the WTC attacks' tawdrily pointless one ("enjoy a lap dance and then go kill some Americans, stir up the country and fatten the wallets of war contractors"). The film's cult built on DVD, the director got a big head, and then damaged his handiwork with the later cut as Barnes describes. After seeing it I made a point to buy a disc with the original version.