re: Enders Game - in the top 5 for the worst and most stupid movie ever

As I'm sure others have mentioned, the movie didn't do the source material justice. You have to understand, the Formics did not originally see the humans as sentient beings. Because of the structure of their society, and how they communicated, they couldn't understand that humans were individuals, not drones. They didn't understand that the death of each human was analogous to the death of one of their queens.

The Formic Queen, in the novel, conveys to Ender “We did not mean to murder, and when we understood, we never came again.” During the final battle, the queen laments “They did not forgive us, she thought. We will surely die.”

Ender was responsible for the murder of an entire race. Once he understood that the Formics regretted their actions, he knew he couldn't let the species die. In later novels, Ender looks for a home for the Formic queen, so that the species doesn't die out.