Seeing there were children on Lithone, made the opening scene more disturbing. The writers didn't have to give the Lithones children, but they did!!!
The opening scene of the movie shows the audience the lives of the Lithones. The adults talking and doing science while the children are laughing and playing, not knowing their species and planet would be destroy by Unicron.
The writers could have just made the entire species having been created as adults and not reproduce (at least not the same way humans can), but they decided to show how dark and serious the movie is going to be by showing Unicron eating the whole planet along its people, which includes the Lithone children.
Honestly, the writers did a good job to show how evil Unicron is. Showing the destruction of a planet, one that had children on it.












