Children's programmes were dropped from BBC1 after more than 60 years and moved to digital offerings CBBC and CBeebies.
Anne Wood, who also co-produces hit show In The Night Garden, said: "It is dismissive of children.
"There is a certain amount of overlooking of the fact that children's programmes do get a wider audience than people are aware of. Just as children's literature does.
"It ghettoises children's programmes. It is a completely different attitude to the one that scheduled Magic Roundabout before the 5.40pm news."
But Terry Deary, author of the Horrible Histories children's books, which have been adapted into TV shows, said the separation was progress. He said: "It doesn't matter at all. The fact that children's shows have been on BBC1 since the war doesn't mean they should continue, and to hang on to them would be a very backward step.
"Ghetto is a very emotive word, and implies the children's channels are inferior. Children's shows on the children's channels is perfectly logical."
Joe Godwin, director of BBC Children's, said: "Far from being a cynical move, we're just following where our audience has already gone."