Celebrity Big Brother host Dermot O'Leary has criticised the decision to change the show's format after the row over alleged racist bullying last year.
"I thought it was a mistake," he told BBC Radio 1's Newsbeat.
"I still think it's a good show and I don't think anyone should apologise for what happened last year. It conjured up debate and asked serious questions."
Big Brother: Celebrity Hijack, which sees stars act as the voice of Big Brother, has launched on Channel 4.
Little Britain's Matt Lucas was the first star to set the rules during the live launch.
The rest of the series will feature footballer Ian Wright, pop impresario Malcolm McLaren and comedians Jimmy Carr and Joan Rivers.
They will set tasks, invent rules and talk to contestants in the diary room.
The 12 housemates, who have been described as "pure prodigies", include an Olympic boxing hopeful, a classical musician and the chairman of the Scottish Youth Parliament.
"Rather than cast someone who's desperate to be on television, they've gone out of their way to cast people who probably wouldn't normally apply to be on it," said O'Leary.
The change in format follows the furore surrounding 2007's Celebrity Big Brother, when Bollywood actress Shilpa Shetty was the victim of alleged racist bullying by fellow contestants Jade Goody, model Danielle Lloyd and singer Jo O'Meara.
A record 45,000 people complained to Ofcom about the incident. It ruled that Channel 4 had made "serious editorial misjudgements" in its handling of the incidents.
Apart from the launch show, this year's show will not be screened on Channel 4, with nightly updates moving to digital channel E4.
Little Britain's Matt Lucas was the first celebrity to take part
The housemates include 19-year-old boxer Anthony Ogogo, from Suffolk, who won a gold medal for Britain at the 2004 Junior Olympics and hopes to compete in Beijing this summer.
Liam Young is an internet entrepreneur from Liverpool, who started selling web space aged eight, while Latoya Satnarine is a professional dancer who has appeared in videos by Madonna, Jamelia and Craig David.
Beauty queen Jade Eden, a former Miss Essex, is a member of Mensa.
Other contestants include politician John Loughton, violinist Calista Robertson, Mobo-nominated songwriter Nathan Fagan-Gayle and car racing champion Jeremy Metcalfe.
The group of 12 is completed by Oxford-educated conceptual artist Amy Jackson, fashion designer Jay Wilson and acrobat siblings Emilia and Victor Arata.
Victor is the 3/1 favourite with bookmaker Ladbrokes to take home the £50,000 prize.