The jazz pop singer claimed that people enjoy the more sadistic elements of other reality talent shows.
Asked why Must Be The Music was cancelled after just one series, Cullum told Metro: "Because not enough people watched it. Maybe it wasn't cruel enough.
"The inherent drama in those shows is the human interest element - when you see people with their screws loose getting pushed around by people who should know better."
He added: "That's what's enjoyable about those shows, no matter how much we don't want to admit it. There wasn't much of that in Must Be The Music.
"It was trying to find a different type of act but those shows are so ingrained in our culture if one deviates from the format people say, 'That's not how it's supposed to be'."
The first run of the show was won by singer-songwriter Emma's Imagination, aka Emma Gillespie, who beat The Pictures and Missing Andy to the £100,000 top prize.
Sources claimed in December that the Sky1 show was too expensive to be recommissioned for a second series.
Watch the Emma's Imagination 'This Day' music video below: