Miracle Day - which ran for 10 episodes in 2011 - was a co-production between the BBC and US cable network Starz.
"Whether you like or dislike Torchwood, it has an essence - of madness and cheekiness and sexiness, and fun and darkness, those sort of polar facets of what it's about, of putting those things together - and somehow it lost a bit of that somewhere in the process," Chibnall told Starburst.
"When we were first talking about it, it was something a bit bolder, a bit cheekier. It may just come back to the fact that one of the great essences of Torchwood was taking those American tropes and doing them in Wales.
"In a way, that's what made Torchwood so brilliantly odd. Once you put it in California, it becomes more like other shows."
Chibnall - whose new series Broadchurch launches in the coming months on ITV - also cast doubt on the likelihood of another Torchwood series in the future.
"It's entirely down to [creator] Russell [T Davies] - I would expect he will have other things he'll want to write, to be honest," said Chibnall.
Davies insisted in October last year that Torchwood is "not officially" cancelled and hinted that the show could still return.
"It's in a nice limbo where it can stew - those shows can come back in ten, 20 years time," he said.
> Torchwood writer Jane Espenson 'proud' of Miracle Day
> Torchwood revival still possible, says Starz exec
Watch Russell T Davies talk Torchwood: Miracle Day with Digital Spy below: